Docstoc

Songwe Airport - Design Review Engineering Report-13OCT09

Document Sample
Songwe Airport - Design Review Engineering Report-13OCT09 Powered By Docstoc
					Songwe Airport: Comprehensive Pavement Design Review Engineering Report
REVISE COVER PAGE

INSERT MOTR Logo

Government of The Republic of Tanzania Tanzania Airports Athority (TAA)

GovernmenGovernment of Kenya Construction of Pavements and Buildings at Songwe Airport in Mbeya, Tanzania
Airport Pavement Design Review Engineering Report
Engineering Report No. SAT09T1 Office of the Deputy Prime Minister and Ministry of Local Governement

© 2009 Kensetsu Kaihatsu Limited

Kundan Singh Construction Ltd Kensetsu Kaihatsu Ltd

October, 2009

Songwe Airport: Comprehensive Pavement Design Review Engineering Report

CONFIDENTIALITY AND © COPYRIGHT This document is for the sole use of the addressee (Tanzania Airports Authority (TAA), Government of the United Republic of Tanzania), Kundan Singh Construction Ltd., and Kensetsu Kaihatsu Limited. The document contains proprietary and confidential information that shall not be reproduced in any manner or disclosed to or discussed with any other parties without the express written permission of Kensetsu Kaihatsu Limited and Kundan Singh Construction Ltd. Information in this document is to be considered the intellectual property of Kensetsu Kaihatsu Limited in accordance with Kenyan copyright law. This report was prepared by Kensetsu Kaihatsu Limited for the account of Kudan Singh Construction. The material in it reflects Kensetsu Kaihatsu Limited’s best judgement, in the light of the information available to it, at the time of preparation. Any use which a third party makes of this report, or any reliance on or decisions to be made based on it, are the responsibility of such third parties. Kensetsu Kaihatsu Limited accepts no responsibility for damages, if any, suffered by any third

© 2009 Kensetsu Kaihatsu Limited

party as a result of decisions made or actions based on this report. ©2009 Kensetsu Kaihatsu Limited

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

FORMAT OF REPORT  COPYRIGHTS  EXECUTIVE SUMMARY  OVERALL SUMMARY  TABLE OF CONTENTS  LIST OF TABLES  LIST OF FIGURES  LIST OF EQUATIONS  NOTATIONS, SYMBOLS AND TERMS

TABLE OF CONTENTS

CHAPTER 1 1. INTRODUCTION 1.1 Background 1.1.1 Status of Phase 1 Works 1.1.1.1 Pavement Works 1.1.1.2 Arrival Building 1.1.1.3 Control Tower 1.1.1.4 Fire and Rescue Building 1.1.2 Works Under Construction 1.2 Background of Design Review of Songwe Airport Pavement Structure 1.2.1 Neccessity for Design Review

© 2009 Kensetsu Kaihatsu Limited

1.2.2 Scope of Study and Works 1.2.3 Songwe Airport Project and Surrounding Areas 1.2.4 Geophysical Details of Songwe Airport in Songwe within Mbeya Region of Tanzania 1.3 Relevant Documents and Records 1.4 Brief Background of Project Area

Page ii

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

1.4.1 Climate and Vegetation 1.4.2 General Topographic, Geographic and Existing Conditions 1.5 Geological Formation, Subsoil Conditions and Ground Profile in General 1.6 Determination of Pavement Structural Design 1.6.1 Determination of Total Pavement Thickness Required 1.6.2 Thickness of Subbase 1.6.3 Thickness of Surface Course 1.6.4 Thickness of Base Course 1.6.5 Thickness of Non-Critical Areas 1.6.6 Typical Cross-section 1.7 Comparison of Various Options 1.7.1 Comparative Analysis of Structural Capacity 1.7.2 Comparative Analysis of Deformation Resistance 1.7.3 Cost Comparative Analysis 1.7.4 Construction Time Comparative Analysis 1.7.5 Derivative Comparison (1) Costs (2) Structural Capacity (3) Deformation Resistance (4) Construction Time 1.7.6 Comparative Conclusions

CHAPTER 2 2. BASIC SAMPLING AND SURVEY PROCEDURES IN BRIEF 2.1 Preliminary Field Survey 2.2 Basic Sampling Regime

© 2009 Kensetsu Kaihatsu Limited

2.3 Geological and Soil Survey in General 2.4 Groundwater Survey in General

2.5 Ground Movement Survey in General

CHAPTER 3 3. TESTING AND INVESTIGATION REGIMES ADOPTED 3.1 Design Criteria of Testing, Investigation and Analytical Regimes 3.1.1 Preamble

Page iii

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

3.1.2 Postulated Failure Mechanism of Pavement and Subgrade Layers 3.2 In-situ and Laboratory Testing 3.2.1 Determination of Basic In-situ Material Properties 3.2.2 Brief Introduction of In-situ and Laboratory Tests Undertaken 3.3 Summary of Laboratory Methods of Testing 3.3.1 Specific Gravity 3.3.2 Atterberg Limits 3.3.3 Sieve Analysis 3.3.4 Natural Moisture Content 3.3.5 Dry and Bulk Density 3.3.6 Aggregate Tests 3.3.7 Compaction Characteristics 3.3.8 Compressive Strength (UCS) and Bearing Capacity (CBR) 3.3.9 Durability

3.4 Summary of In-situ Methods of Testing 3.5 Schedule and Summary of Tests Performed 3.5.1 Laboratory Tests 3.5.2 In-situ Tests 3.6 Proposed Post-Construction Tests 3.6.1 Deflection Tests 3.6.2 Core Sampling ad Testing

CHAPTER 4 4. RELEVANT ENGINEERING CONCEPTS AND THEORIES APPLIED 4.1 Outline of Methodology of Data Analysis, Evaluation and Criteria for Suitability 4.2 Determination of Basic Parameters 4.2.1 Standard Soil Model Expressions Concepts Applied for Analyzing Impact of Environmental Factors

© 2009 Kensetsu Kaihatsu Limited

4.2.2

 Effect of Swelling  Effect of Variation In Design Moisture Content  Seasonal Effects On Bearing Capacity and Resilient Modulus 4.3 Bearing Capacity Analysis 4.3.1 4.3.2 Derivation of correlation of N-value, UCS and CBR Derivation of CBR and qu Relations for Stiff Geomaterials

4.4 Consolidation and Settlement Related Analysis

Page iv

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

4.4.1 4.4.2

Estimation of Consolidation and Shear Stress Paths Analyzing Construction History for Settlement Prediction

4.5 Shearing Strength and Critical State Analysis 4.5.1 4.5.2 Analysis of a Soil Element along the Slip Failure Plane Application of Modified Critical State Soil Mechanics

4.6 Deformation Resistance Analysis 4.6.1 4.6.2 4.6.3 Application of Deformation Concepts Determination of Modulus of Deformation Parameters Computation of Linear Elastic Range

4.7 Geophysical Survey Analysis 4.8 Concepts Applied for OPMC Stabilization 4.8.1 4.8.2 Theoretical Considerations Proposed Method of Determining Optimum Batching Ratio (OBR)

CHAPTER 5 5. MATERIALS CHARACTERIZATION AND ANALYSIS OF TEST RESULTS 5.1 Basic Physical and Mechanical Parameters 5.2 Correlation Between Physical, Mechanical and Strength Parameters 5.3 Dynamic Cone Penetration (DCP) Test Results 5.4 Aggregate Test Results 5.5 Summary Tables of Bearing Capacity and Shearing Strength Parameters 5.6 Bearing Capacity Test Results

5.7 Consolidation Test Results 5.8 Shearing Strength Test Results 5.9 Modulus of Deformation, Elastic Modulus and Linear Elastic Range 5.10 Deformation Properties and Linear Elastic Range 5.11 Durability Test Results

CHAPTER 6

© 2009 Kensetsu Kaihatsu Limited

6

APPLICATION OF TEST RESULTS

6.1 Basic Physical and Mechanical Parameters 6.2 Correlation of Physical, Mechanical and Strength Parameters 6.3 Dynamic Penetration Test Results 6.4 Aggregate Test Results 6.5 Laboratory Test Results 6.6 Bearing Capacity Test Results 6.7 Consolidation Test Results

Page v

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

6.8 Shearing Strength Test Results 6.7.1 Application of Principle Stresses within the Soil Elements 6.7.2 Shearing Strength Test Results 6.9 Modulus of Deformation and Elastic Modulus Test Results 6.10 Deformation Properties and Linear Elastic Range 6.11 Durability Test Results

CHAPTER 7 7. CHARACTERIZATION OF PAVEMENT STRUCTURAL DESIGN CHAPTER 7 7. PAVEMENT STRUCTURAL DESIGN 7.1 Scope 7.2 Fundamental Design Philosophy 7.3 Comparison of Design Data with Various Design Criteria 7.3.1 Comparison of Design Criteria for Physical, Strength and Bearing Capacity Parameters 7.3.2 Comparison of Applicable Specification Criteria for Stabilized Natural Gravel and Design Parameters 7.3.3 Comparison of Modulus of Deformation Parameters 7.3.4 Comparison of Durability Parameters 7.3.5 Comparison of Tested Material Properties and Secified Requirements 7.3.6 Conclusions Regarding Design Parameters 7.3.7 Adopted Design Criteria 7.4 Evaluation of Air Traffic Volume and Growth 7.5 Engineering Analysis of Geomaterial Properties 7.6 Evaluation of Strength of Existing Subgrade 7.6.1 Relatively Stable Geomaterials

© 2009 Kensetsu Kaihatsu Limited

7.6.2 Analysis of Problematic and/or Expansive Soils 7.7 Determination of Pavement Structural Design 7.7.1 Determination of Total Pavement Thickness Required

CHAPTER 8 8. ANALYSIS OF TIME DEPENDENT STRUCTURAL SOUNDNESS 8.1 Analysis of Structural Capacity Deterioration with Time Progression based on the SCDR Model

Page vi

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

8.1.1 Definition of Structural Failures 8.1.2 Fundamental Theories/Concepts Applied in Developing SCDR Model (1) Theories and/or Concepts Considered 8.1.3 Analysis of Structural Capacity 1) Initial Structural Capacity 2) Deterioration of Structural Capacity with Time Progression 3) Analysis of Influence of Environmental Factors 8.2 Analysis of Time Dependent Structural Capacity for Varying Designs of Songwe Airport

CHAPTER 9 9. CONCLUSIONS AND RECOMMENDATIONS 9.1 Main Conclusions 9.2 Basic Recommendations

MAIN REFERENCES APPENDICES Appendix I Appendix II U.S. Army Corps of Engineers and Federal Aviation Administration (FAA) Design Method International Civil Aviation Organization (ICAO) Standards and Procedure for Aerodrome Design Appendix III Appendix IV 747 Airplane Characteristics – Airport Planning – Boeing Commercial Airplane Company Annex 14 Volume of the ICAO

© 2009 Kensetsu Kaihatsu Limited

Page vii

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

LIST OF TABLES Table 1.2.1 Relevant Clause 8 of The Fourth Edition 1987 FIDIC Conditions of Contract Table 1.2.2 Relevant VE Sub-Clause 13.2 of The Bank Harmonized Edition of the Conditions of Contract – IFCE, FIDIC Table 1.6.1 Summary of Main Design Parameters Adopted Table 1.7.1 Conversion Co-efficient for the Calculation of �������� Table 1.7.2 Summary of Comparison of Costs Table 1.7.3 Structural Capacities based on �������� Values for varying Otions (Target �������� Value = 30) Table 1.7.3 Comparison of Deformation Resistance Based on Elastic Modulus for Varying Options Table 5.1.1 Summary of Grading Characteristics of Songwe Airport Soils Table 5.1.2 Summary of Subbase Material Test results for Songwe Airport – Mbeya Table 5.2.1 Summary of Stabilization Test Results of Songwe Airport km2+200LHS Subbase Stockpile Material Table 5.2.2 Summary of Lime-Stabilized Songwe Airport km2+200LHS Subbase Material Test Results Table 5.2.3 Summary of Cement-Stabilized km2+200LHS Subbase Material Test Results Table 5.2.4 Summary of UCS for Songwe Airport Stabilized Subbase Material added 1%, 2% & 3% PPC Table 5.2.5 Summary of UCS for Songwe Airport Stabilized Subbase Material added 1%, 2% & 3% PPC Series 5.2.1 Tables and Figures for Dynamic Cone Penetration Results for Songwe Airport - Runway Ch2+000 to Ch2+400 Table 5.2.2 CBR Data and CBRM Values from Dynamic Cone Penetration Results for Songwe Airport Runway Ch2+000 to Ch2+400 Table 5.4.1 Lab Sieve Analysis Results of Coarse Aggregate for Songwe Airport - Runway Table 5.4.2 Lab Sieve Analysis Results of FineAggregate for Songwe Airport - Runway Table 5.4.3 Fineness Modulus of Fine Aggregate for Songwe Airport - Runway Table 5.4.4 Lab Sieve Analysis Results of CRS for Songwe Airport - Runway Table 5.4.5 Summary of Stone Quarries Materials Tests Results for Songwe Airport in Mbeya Table 5.5.1 CBR (Mean) Computations for Songwe Airport in Mbeya, Tanzania Fig. 5.5.1 CBR Mean values at Chainages on Songwe Airport Runway Table 5.5.1-2 Dry and Wet CBR (Mean) Computation Table 5.5.2 Summary of Lime-Stabilized Subbase Material Tests Results for Songwe Airport Project Table 5.5.3 Summary of Cement-Stabilized Subbase Material Tests Results for Songwe Airport Project Table 5.7.1 Summary of Consolidation Stress Parameters Derived from Laboratory Tests Table 5.8.1 Summary of Shearing Strength Parameters Table 5.8.2 Computed and Measured Mean UCS at different Cement Contents Table 5.8.3 Summary of Shear Stress Parameters Derived from In-situ Tests Table 5.9.1(a) Summary of Modulus of Deformation Parameters from Lab Test Results Table 5.9.1(b) Summary of Modulus of Deformation Parameters from In-situ Test Results Table 5.9.2 Summary of Modulus of Deformation Parameters from In-situ Test Results Table 5.10.1 Summary of Modulus of Deformation Parameters from Laboratory Test Results Table 5.11 Average Percentage of Material Loss for 1%, 2%, & 3% Cement-treated Materials Table 7.2.1 Summary of Major Design Considerations Table 7.2.1 Summary of Major Design Considerations Table 7.2.2 Technical Specifications for Boeing Aircraft detailing the B747-100 Table 7.2.3 General characteristics of the Model 747-100 Aircraft Table 7.2.4 Maximum Pavement Loads of the Model 747-100 Aircraft Table 7.3.1 Comparison of Design Criteria - Physical, Strength & Bearing Capacity of Stabilized Materials Table 7.3.2 Comparisons of Spec. Criteria -Stabilized Natural Gravel & Design Parameters - This Study Table 7.3.3 Comparisons of Ranges of Elasticity Modulus for Structural Design from Various Sources Table 7.3.4 Comparison of design Criteria for Durability Tests Based on Data from American Portland Cement Association (APCA) and This Study

© 2009 Kensetsu Kaihatsu Limited

Page viii

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 7.3.5 Comparison of Songwe Airport Material Results to Specified Material Requirements Table 7.7.1 Summary of Main Design Parameters Adopted Table 8.2.1 Summary of Main Parameters Adopted for Analysis for Varying Designs Table 8.2.2 Structural Depreciation Factor for ORIGINAL Design option. Table 8.2.3 Structural Depreciation Factor for U.S. FAA – ICAO Based Design option. Table 8.2.4 Structural Depreciation Factor for OPTION1 Proposed Type I Design Table 8.2.5 Structural Depreciation Factor for OPTION2 Proposed Type II Design Table 8.2.6 Structural Depreciation Factor for OPTION3 VE Based Design Table 8.2.8 Structural Depreciation Factor with Time Progression for Varying Design Options

© 2009 Kensetsu Kaihatsu Limited

Page ix

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

LIST OF FIGURES Fig. 1.1 Fokker F50 Aircraft and the Boeing 737-700 Plane Plate 1.2 Site photo depicting progress and condition of runway pavement and buildings Fig. 1.1 Lay Out of Mbeya Fig. 1.2 Sattellite Image of Songwe Airport in Mbeya Region, Tanzania Plate 1.3 - Photos Superimposed on Sattelite Imagery showing the Airport Figure 1.4 – Location map of Songwe and surroundings Fig. 1.3 Map of Mbeya Region

Fig. 1.5 Simplified geological/tectonic map of Tanzania
Fig. 1.6 Major Soil Groups of Tanzania Fig. 1.7 Soil map of Mbeya region Fig. 1.6.1 Typical Cross-section based on US FAA / ICAO Design Methods Fig. 1.7.1 Typical Cross-section of ORIGINAL (Existing) Design Fig. 1.7.2 Typical Cross-section Based on US FAA / ICAO Design Methods Fig. 1.7.3 Typical Cross-section of Type I Proposed Design Fig. 1.7.4 Typical Cross-section of Value Engineering (VE) Based Design Fig. 1.7.5 Typical Cross-section of Alternative Design Fig. 1.7.6 Typical Cross-section of Type II Proposed Design Fig. 1.7.7 Schematic Cross-section of varying Layers of ORIGINAL (Existing) Design Fig. 1.7.8 Schematic Cross-section of varying Layers of US FAA / ICAO Based Design Fig. 1.7.9 Schematic Cross-section of varying Layers of Type I Proposed Design Fig. 1.7.10 Schematic Cross-section of varying Layers of Value Engineering (VE) Based Design Fig. 1.7.11 Schematic Cross-section of varying Layers of Alternative Design Fig. 7.8.12 Schematic Cross-section of varying Layers of Type II Design Fig. 1.7.13 Graphical depiction of summarized comparison of Maintenance Costs Figure 4.11 – Effect of gradation index on Mechanical Stability Figure 4.12 – Effect of gradation index on Bearing capacity Figure 4.13 – Correlation between mechanical stability, MS and bearing capacity, BC Figure 4.14 (a) - (h) Method of Enhancing Mechanical Stabilization of Geomaterials (After Mukabi, 2001a) Figure 4.15 Schematic representation of Grading curves generating Graphical Lines Depicted in Fig. 4.16 (After Mukabi, 2001a) Fig. 4.16 Graphical Representation of New Batching Ratio Method (After Mukabi, 2001a) Fig. 7.2.1 General Dimensions of the Model 747-100 Aircraft Fig. 7.2.2 Ground Clearances – Passenger Configurations Model 747-100 Aircraft Fig. 7.2.3 Landing Gear Footprint for Model 747-100 Aircraft Fig. 7.2.4 Landing Gear Loading on Pavement - Model 747-100 Aircraft Fig. 7.2.4 Flexible Pavement Requirements – U.S. Army Corps of Engineers Design Method S-77-1 and FAA Design Method - Model 747-100 Aircraft Figure 8.1.1 Depiction of Determining Period and Level of Maintenance Based on the SCDR Model Figure 8.2.1 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting �������� “WITH Maintenance” Scenario as well as “WithOUT Maintenance” effect for ORIGINAL Design Figure 8.2.2 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting �������� “WITH Maintenance” Scenario as well as “WithOUT Maintenance” effect for USFAA-ICAO Design

© 2009 Kensetsu Kaihatsu Limited

Page x

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Figure 8.2.3 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting �������� “WITH Maintenance” Scenario as well as “WithOUT Maintenance” effect for OPTION1 Type I Design Figure 8.2.4 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting �������� “WITH Maintenance” Scenario as well as “WithOUT Maintenance” effect for OPTION2 Type II Design Figure 8.2.5 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting �������� “WITH Maintenance” Scenario as well as “WithOUT Maintenance” effect for OPTION3 VE Based Design Figure 8.2.7 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting �������� “WITH Maintenance” Scenario as well as “WithOUT Maintenance” effect for Varying Designs

LIST OF FLOWCHARTS Flow Chart 4.1 Proposed Batching Ratio Method (After Mukabi, 2001a)

LIST OF PLATES Plate 1 - Photos Superimposed on Sattelite Imagery showing the Road Plate 3.6 Checking DCPT Equipment and DCP Testing

© 2009 Kensetsu Kaihatsu Limited

Page xi

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

LIST OF EQUATIONS
 q    mc  u vmc    q PI   q  qu imc 

 E    mc  50 vmc    EUPI   EU  E50 imc 
 E    mc  max vmc    EmPI   Em  Emax imc 
  CBR   gl     1    f OPMC   gi   umc     mc     q PI   q     CBR   gl   f 1OPMC      gi  imc    
gi

(4.1) (4.2) (4.3)



  gl PI  BC



(%)

(4.4) (4.5) (4.6) (4.7) (4.8) (4.9) (4.10) (4.11) (4.12) (4.13) (4.14) (4.15) (4.16) (4.17) (4.18) (4.19)

 CBRm  35(%)

  gl ln CBR   gi umc    mc   gl ln CBR   gi imc    q PI   q (%)    

 sc  sc ln  sc   sc

 DMC   gl ln PI   gl

(%)

PI d  Ap e PI w
Bp

D w mc  Am e Bm D d mc
wdr   gl ln CBR w   gi

ddr   gl ln CBR d   gi

 wMr   gl ln M r   gi
NSPT = NNS {D2/Di}2 × D12/d × Wh/W140 × Hd/D30 N60 =
E mN C B C R C S fR

NSPT = ANf qu + BNf −1 NSPT = ANv × PR
−1 q u = Aqu × PR −1 CBR = ACBR × PR CBR  { gl q u   gi }  f OPMC

(%)

(4.20) (4.21) (4.22)

© 2009 Kensetsu Kaihatsu Limited

 CBR   gl    qu    f  gi    

1

OPMC

(kgf/cm2) (%)

  CBR   gl     1    f OPMC   gi  umc      mc     q PI   q  CBR   gl   1      f OPMC    gi   imc  

 CBRUS  500 0.9 S r   CBR S0.1 S r 

(4.23)

   A  CSR  B

(4.24)

Page xii

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

 '   SR  SR /  SR
 
K I     CSR .CSR
NC K oNC .qmax oc  Ko . A .CSR NC

(4.25)

m ax I

(4.26)

oc qmax 

KoNC

(4.27)

NC   PC'OC  Pf' NC KO q 'fOC   NC  OC NC  ' pCNC  K O  K O . A CSR   

(4.28)

  K  'fOC   NC  f NC   KO  K . A CSR   
NC O OC O 

1

' NC

(4.29)
10 

ij ST  H i

i CC 1  ei

i 1, j 1

 log

 P ij  P K iC  o ij P 0 

   

(4.30)

C ci 

e i log 10 P0  P  / P0 
k Psc (10i  1)

(4.31)

P0ij 

(4.32)

 SR  0.0422  '0.0455

(4.33)

'

ANf (qu ) max  Af Bf
(4.34)

  q max  '  Sin 1    2 p' f  1 3q max   

(4.35)

 1 1 p 'f  0.5 qmax     Sin ' 3 
 1 1 p' f  0.5 qmax     Sin ANf qU max  A f / B f ' 3   

(4.36)

© 2009 Kensetsu Kaihatsu Limited



 

(4.37)

q u   gl ln CBR   gi

(kgf/cm2)

(4.38)

(4.39)

(4.40) q ηmax )/ KI − ×
I

CSR

Page xiii

Ψ′ = ( = Ψ ′ p′

⁡

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

���� = Γ − �������� ������������′ μ ′ �������� = ������������ (Γ − �������� )/��������
′ �������� = Ψ ′ ������������ (Γ − �������� )/�������� I = αCSR ηc / + βCSR ′ ν ����N= �������� /{�������� = �������� × �������� × �������� /���� } ln
0. eff   SC7 xeff DR DI λa λa ) = ij − λm p′ E50 n E m ax  x q (kgf / cm 2 ) (0.0996 qu  0.0104 ) (

(4.41) (4.42) (4.43) (4.44) (4.45) (4.46)

(4.47)
(4.48) (4.49) (4.50) (4.51)

ij C Emax  139x dg x10m xe0.0782qu (kgf / cm2 )
' Go  2360 (2.17  e) 2 (1  e)( o ) 0.6

 
���� ���� ����

ij a ELS

 a ij 50  ij  ELS  a ijmax  A
1 5 3

(%)

2 = ������������ ���� 2 ����0 /����2 {���� 2 ���� 2 }���� −5/2

(4.52) (4.53) (4.54) (4.55) (4.56)

���� ���� ���� = ����0 ����/2���� ���� ���� ���� = 3��������(���� 2 ���� 3 )

q n  C N C S C d C bC g C  p o N q S q d q iq bq g q  1 / 2BN  Sd  i b g 

S q  SC  d q  dC 

S C  Sc  1 Nq d C  dc  1 Nq

(4.57) (4.58) (4.59)

g r  g q  1  sin 2 

g c  e 2  tan 
© 2009 Kensetsu Kaihatsu Limited
v Rc  f df , ti , Pc , Pe , te,  ms



4   E p t 4 = 1  6CV2  3CV4 PSt

 

 dh  f  ' , ' , p'oc , qoc ,  'oc , f yi ,  ijo  f f f



(8.1) (8.2) (8.3)

    III Pst . 4
K = vLEF

(8.4) (8.5)

Page xiv

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009
2  rd  coeht sin h2  0  t  o 0.5

E(t )  0.5C02 e 2ht

   w  h Cos w  h 
a 2 0 2 2 2 0

(8.6)

2 0.5

t   0  f r sin 2 w02  h 2







0.5

t  0



(8.7) (8.8)

dE (t ) d 2  1 / 2 a  rd  1 / 2 f r  2 dt dt





  arctan
b
b



2 h 0   2
2 0



(8.9)



f0

2 0

 w 2   4h 2 2
f0  4h 2 2

f0



0.5

(8.10)

4



0.5

(8.11)

b

2

(8.12)

  arctan



2hw    2
2 0



(8.13) (8.14) (8.15) (8.16)
n

 rd   rd Z 1t    rd Z e iwt

n

n  2 rd  2 n  3 n  Gn  n t 2 Z 2 Z 2 t

nrd     n e ik n Z  Fn e  ik n Z

 n    ik n G n E n e ik Z  Fm e  ik Z 
n

(8.17) (8.18)

kn  

pn Gn
en    f n   en    f n  

Anm   

(8.19)

© 2009 Kensetsu Kaihatsu Limited

i  K n  t  2 n   n Z t     rd  2  ne  rd 1   i  K Z  w t  t 2  Fne n   

(8.20)

n 

n  nei  K n  t     2 rd  ikn   i  K Z  wt     Fne n   

(8.21)

  21     2  s  

n 
g 

(8.21)
1 2

* * * * f y1  ij  xij ij  xij







 RD1  0

(8.22) (8.23)

* vp dxij  B1* A1* deij  xij d vp 

Page xv

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

vp vp d vp  deij deij






1

2

(8.24)
~ ' 12  M *1n  m '  ma (1)   0  

* * * * g1   ij  xij  ij  xij





(8.25a) (8.25b) (8.26) (8.27) (8.29)

~* ' ' fb  *   M m1n  m  ma(1)  0 0



~ ' ' M *     n  m  mc 

   A  CSR  B

 

K I     CSR .CSR

m ax I

oc qmax 

KoNC

NC K oNC .qmax oc  Ko . A .CSR NC

(8.30)

q

'OC f

NC   PC'OC  Pf' NC KO   NC  OC NC  ' pCNC  K O  K O . A CSR   

(8.31)



'OC f

NC ' NC   KO   NC  f OC NC   KO  KO . A CSR   

1

(8.32)

O (  ij *' 

1 Z  0 exp Z  Z ' /   ij' Z 'dZ ' T

(8.33) (8.34)

' 1 ~   b  * * * *  g 1   ij  xij  ij  xij  2  M * 1n  'm  b   0  mb 

~*  ' b  f b  *   M m1n  'm 0   b   0   mb 

(8.35)

 ' b  ~ M *     n  'm   b    mb 

(8.36)

 RSF  1  0.01C fAC  FCAC xC BC  FCBC xC SB  FCSB  f f
© 2009 Kensetsu Kaihatsu Limited
t e f SC  f SC x log N t1.5

e Re f SC  f RL  f SC  RDeff . x rf





(8.37) (8.38) (8.39) (8.40)





1

f

t

SC

 ASC N t  BSC N t  C SC
���� ���� ������������ = ������������ × ℓ������������0.62 −1

× 1+

���� 0.1������������ �������� ���� ������������

× ℮0.01��������

(8.41) (7.1)

�������� = ����1 ����1 + ����2 ����2 + ⋯ �������� �������� �������� =
�������� �������� ������������ ������������3 + ������������ ������������ 1 1 3 �������� �������� + ������������ ������������ 1 3 �������� �������� + ������������ ������������ 1 3 �������� �������� + +�������� �������� 1 3 �������� �������� + �������� �������� 1 3

100 − �������� ������������3

1

3

�������� �������� �������� �������� �������� ������������ + ������������ + ������������ + ������������ + �������� + �������� + 100 − �������� ���� ������������ = ℮ 0.01������������ ��������
����

−1

(8.42)

Page xvi

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

���� ���� ���� ���� ������������ = ���������������� × ���������������� . × ������������ ���� ���� ���� ������������ = ������������ × ������������

(8.43) (8.44)

© 2009 Kensetsu Kaihatsu Limited

Page xvii

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

NOTATIONS, SYMBOLS AND TERMS N = number of equivalent standard axle repetitions niv = initial number of vehicles daily in one direction Cv = proportion of commercial vehicles expressed in decimal form Gr = annual growth rate expressed in decimal form dl = proportion of vehicles using the design lane as a decimal (dl = 1 in this case) PDL = design life for the pavement in years EF = axle load equivalency factor expressed as : EF = (Ls/80)4.5 RDeff. = Damaging effect LW = Load on the axle group ELW = 8.2 tones in the case of a single axle with dual tyres. Values of ELW for other axles adopted in this study are given in Table 2.1 below C = an exponent considered as C= 4 in this case IGf = Intensity of Growth factor related to increase in cumulative ESAL Wt = f (PSF, RSF, CRF, PCF )x Rf PSF = Pavement structure factors i.e. upper pavement layer thickness RSF = Roadbed soil factors i.e., soil Resilient Modulus CRF = Climate related factors i.e., drainage and evapotranspiration coefficients PCF = Pavement condition factors i.e., Terminal Serviceability Index Rf = Reliability Factor, where Rf = Wt/WT > 1 and WT is traffic prediction factor PSI = Present Serviceability Index SV = Slope Variance C = Lineal measurement of cracking per 100m2 area P = Bituminous patching in m2 per 1000m2 area RD = Rut depth in cm for both wheel tracks measured with a 3m straight edge  PSI = PSITR + PSISN + PSIMR  PSI = Total loss of serviceability (P0-Pt)  PSITR = Serviceability loss due to traffic loading (ESAL)  PSI SW = Serviceability loss due to swelling of roadbed soil PSIMR = Serviceability loss due to deterioration of the quality of pavement material

Pt
PtA Ptp

A

 log N t 10

© 2009 Kensetsu Kaihatsu Limited

= Actual performance related to PSI = PtA = log Wt = predicted log Nt logwt = log (Rf x WT) = logWT + log Rf Rf > 1 and log Rf > 0 log Rf = (log Wt – log WT) > 0  = log Nt – log NT d + = Section survival of design period ESAL d NT = Actual design period ESAL Nt = Actual ESAL to Pt SCDLn = SCyn - FRL (Sceff.)n SCY = The total structural capacity required to support the overlay traffic over existing subgrade conditions SCeff = The effective structural capacity of the existing pavement immediately prior to the time of overlay, and has reflected the damage to the point FRL = The remaining life factor which accounts for damage of the existing pavement as well as the desired degree of damage to the overlay at the end of the overlay traffic where FRL < 1.0 n = A constant exponent which varies with the type of pavement system used in the analysis CBRus = 500(0.9-Sr) x CBRs (0.1+Sr) CBRus = Unsoaked CBR CBRs = Soaked CBR

Page xviii

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Sr

=

( f = s)

 s max   SR i SP

Saturation level expressed as a fraction of 100 percent.

( f = Time related swell factor s) ( max = Maximum Swell s)  = Surcharge related variable defined as a ratio of the applied surcharge pressure against the effective SP upper pavement layer surcharge pressure over the subgrade determined as the standard surcharge pressure i.e.



U ss U sp

© 2009 Kensetsu Kaihatsu Limited

( )i = Initial Rate of Swell SR  PSIsw = 0.00335VRPS(1-eSRDL) VR = Potential vertical rise due to swell in cm PS = Probability of swell as a percentage of total area subject to swell  = Rate of swell SR DL = Design Life Dmc = Design Moisture Content in % Vep = Annual evapotranspiration in metres/year LL = Liquid limit of subgrade material (%) CBRUS = Unsoaked CBR CBRS = Soaked CBR PI = Plasticity Index GLSC = Total Aggregate Loss converted in cm linear thickness for Loose Aggregate sections LT = Number of Loaded Trucks in thousands GLc = Total Aggregate Loss converted in cm lineal thickness for exposed sections P = Performance Period = 4 years in this case (counted since the BD study) T = Annual Traffic Volume in both directions in thousands of vehicles R = Annual Rainfall in mm VC = Average percentage of gradient of the road F = Considered to be 0.037 as for lateritic gravels S2 = Variance xi = Value of ith sample N = No. of sample units CV = Coefficient of Variance S = Sample Standard Deviation xav = Average value is computed as VAV = Average Variable qu = Unconfined Compressive Strength qu M r  633 .2qu  178 .5 ( MPa ) Mr CBR = 10.3 CBRd (MPa) M rCor . = Corrected Resilient Modulus MrCBR = 10.3CBRd (Design CBR)  = (MrCBR-362)/MrCBR when MrCBR<362 Mr  = 0.5(MrCBR-362)/MrCBR when MrCBR>362 Mr AMr = Constant dependent on range of Resilient Modulus Mr = -497Wc + 5431 Mr = Resilient Modulus WC = Variation in water content

 ch

d ch

=

Diameter of Chuckhole/Depth of Chuckhole

TR = TMf—T0  TR = Resulting Thickness

Page xix

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

TMf T0

= Modified Thickn = Original Thickness AV TR = Average Resulting Thickness
w

Cor CBRw  500(0.9Sr ) x1   R 
Cor = CBR w

1 Sr 
w

Corrected value to conform to CBR determined during wet season

S

w r

R

Rf Ri Rt

Saturation level determined for Soils Sampled during the wet season Ratio of CBR determined during the wet season to that determined during the dry season. In the case whereby either of the values is unavailable then the ratio of soaked to unsoaked CBR can be adopted from the relation CBRs/CBRus = 0.97-0.027PI (Ref. eqn. (18)) = Roughness Factor = Initial Roughness Value = Terminal Roughness Value

= =

I Gf 

1 100

 G xESAL
i 1 i

n

i

T F R RDeff  RDeff  RDeff

fsd = fRL = f (RDeff, PSF, RSF, PSI) fsd = fRL = 1 - [RDeff. x (1-rf)] rf = Combined contribution of other factors deemed to have had a reciprocal effect on the magnitude of the damaging effect. In this study, P Cf = Cf x fsd Te = TeE x CfP x fsd TeE = Existing thickness. CBRdDD = CBRdBD x fsd

TA 

9.19  3.97 log DTN = Equivalent Thickness Index Total Asphalt Concrete CBR0.4

P(t) = instantaneous tyre force at time t, Pst = E[p(t)] = static (average) tyre force Cv = coefficient of varieties of dynamic tyre force E[ ]= expection operator. 2 4  = 1+6 CV +3 CV (dynamic road factor)

 and ’ are dynamic versions related to the AASHO load equivalent factor (LEF) in the forms:

 I = parameter accounting for wheel configuration for both single or dual tyres  II = parameter accounting for tyre contact pressures. Intuitively
 rd = rebound deflection

© 2009 Kensetsu Kaihatsu Limited

Co= constant representing the initial conditions of loading d=damping factor of the pavement structure related to layer stiffness t = response time measured  = angular frequency  = constant representing the initial position and condition of deflection measurement. fr is the force constant la=axle load.

Page xx

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

CHAPTER 1 1. INTRODUCTION 1.1 Introduction to Project Background The Tanzania Airport Authority (TAA) has received loans from BADEA and the OPEC Fund for the construction of a new airport at Songwe in the Mbeya Region. United Engineering and Technical Consultants (UNETEC) Ltd in association with Crown Tech Consult, were engaged by the TAA in June 2006, to undertake part design, design review and supervision of pavements and buildings at Songwe Airport. The construction of a new airport in Mbeya was first conceived in 1977 which warranted the engagement of Furgo-Cesco Consultants to undertake a site selection study. This was followed up in 1987, with a feasibility study conducted by COWI Consult. The study amongst other things recommended locating the new airport outside the city due to the extent of development in the downtown area. M-Consult were then commissioned in 2002 to carry out a design of the entire airport facilities using the Fokker F50 as the design aircraft with provision for future expansion to accommodate a Boeing 737. In May 2004, however, Sir Frederick Snow & Partners, were instructed to undertake a redesign of the runway, taxiway and aprons in order to facilitate B737 operations.

Plate. 1.1 Fokker F50 Aircraft and the Boeing 737-700 Plane Actual implementation of the project started in July 2004 with the engagement of a local contractor to construct an arrival building, control tower, fire and rescue building, a 3.3km runway, access road, car park and apron up to subbase level. The government then requested its development partners to provide funding for further development.

© 2009 Kensetsu Kaihatsu Limited

It was agreed following a joint site visit and subsequent meeting held on 18th July, 2006, that the Consultant should undertake additional services including the design of a new terminal building, new sewerage treatment works, water supply and treatment system, other connector roads, slope protection schemes and fencing. 1.1.1 Status of Phase 1 Works The Contract for the first phase of the project was signed in July 2004 between the Tanzania Airport Authority and Kundan Singh Construction Company. It comprised the construction of an arrival building, control tower, fire and rescue building, and the construction of a 3.3km runway, access road, car park and apron up to subbase level. As at 31st January, 2007, the status of the works were as follows:-

Page 1

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

1.1.1.1 Pavement Works The runway was constructed to subbase level. The rectification works mentioned in the inception report have now been carried out and the supervising consultant has issued the certificate of substantial completion. The defects liability period ends in April, 2007. The access road was constructed to subbase level from chainage 0+025 to 0+523. The initial 25m which connects the access road to the TANZAM highway has to be constructed. The car park, taxiway and apron have also been constructed to subbase level. 1.1.1.2 Arrival Building Following the Clients decision to construct a new terminal building to cater for both arriving and departing passengers, the works on the arrival building were halted several months earlier. The existing building is to be modified to cater for the office needs of the TAA and other requirements. 1.1.1.3 Control Tower According to the supervising Consultant, progress on the construction of the control tower now stands at 65 percent. Internal and external plastering has been completed however, floor tiling, roofing, sanitary fixtures, painting and other finishing works are yet to be undertaken. 1.1.1.4 Fire and Rescue Building The works on this building is more advanced than all others with progress estimated at 80 percent. The outstanding works relate mainly to finishing and include plumbing and sanitary fixtures, painting, tiling and furniture. 1.1.2 Works Under Construction A detailed description of the Scope of Works under this phase of construction is given in the Contract Documents of the Construction of Buildings and Pavements of Songwe Airport in Mbeya.

1.2 Background of Design Review of Songwe Airport Pavement Structure 1.2.1 Neccessity for Design Review Upon signing of the Contract, the Contractor, in accordance with Clause 8 of The Fourth Edition 1987 FIDIC Conditions of Contract (ref. to Table 1.2.1), undertook monitoring, technical evaluation and geotechnical engineering investigations in order to confirm, more precisely, the engineering properties of the existing soils as well as the behavior of the existing ground and pavement structure. The preliminary results indicate that the existing ground and pavement structure exhibited much higher bearing capacity and strength responses in comparison to the values that may have been considered in the Original Design. As a consequence, the Contractor made a decision to embark on further and more detailed laboratory and in-situ experimental testing, technical evaluation, geotechnical engineering investigations and analyses. This was also in consideration of the fact that it is most likely the Original Design did not take into account the pozzolanic cementetious nature of the existing geomaterial and its immediate response

© 2009 Kensetsu Kaihatsu Limited

Page 2

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

to compaction and the effects of time related consolidation, thixotropy and creep (secondary consolidation). This would certainly therefore have influenced the Original Design Concept, selection of materials and design of the pavement layer configuration. In view of the foregoing facts, and in consideration of the recent International trend whereby emphasis is placed on fostering and enhancing Value Engineering (VE) based approach in the design and construction of civil engineering structures (ref. to Sub-Clause 13.2 in Table 1.2.2), the Contractor made the engineering judgement to undertake a Detail Design Review (DDR) of the Songwe Airport Pavement Structure. Table 1.2.1 Relevant Clause 8 of The Fourth Edition 1987 FIDIC Conditions of Contract
Clause/ SubClause 8.1 Contents Brief Analytical Remarks

Contractors General Responsibilities The Contractor shall, with due care and diligence, design(to the extent provided for by the Contract), execute and complete the Works and remedy any defects therein in accordance with the provisions of the Contract. The Contractor shall provide all superintendence, labour, materials, Plant, Contractors Equipment and all other things, whether of a temporary or permanent nature, required in and for such design, execution, completion and remedying of any defects, so far as the necessity for providing the same is specified in or is reasonably to be inferred from the Contract. The Contractor shall give prompt notice to the Engineer, with a copy to the Employer, of any error, omission, fault or other defect in the design of or Specification for the Works which he discovers when reviewing the Contract or executing the Works.

This Clause clearly indicates that it is the Contractor who is liable to the proper execution of and completion of the Works as provided for in the Contract. On the other hand in accordance with Sub-Clause 8.3 part a) i) on page No.11 of the conditions of Particular Application for this Contract, the Contractor is responsible for ensuring that Sound Engineering Practice is observed at all times and for all aspects of the project. Essentially therefore paragraph 1of this Sub-Clause provides that the Contractor takes full responsibility of ensuring the proper and practical implementation of this Project. The foregoing fact is emphasized by paragraph 2 of the same SubClause, which requires that the Contractor should have the ability to detect any error, omission, fault or other defect in the design or specification for the works, upon which the Contractor has the obligation to notify the Engineer and Employer promptly. The main pragmatic interpretation and implication here is that: 1) The Contractor has the full responsibility of reviewing the design and all other associated, corresponding and/or otherwise relevant documents, in the post-bidding stage (Contract Implementation Stage) to ensure that the works are executed and completed on the basis of sound engineering which will lead to the realization of an excelling civil engineering product. 2) The Contractor is liable hence responsible and obligated to taking prompt action communicating to the Engineer and Employer (Client) any detection that would be an impediment to the realization of 1) above. 3) The Contractor has the liberty to notify the Engineer and the Employer regarding such error, omission, fault or defect in the design or specifications either when reviewing the Contract or executing the Works. 4) In accordance with sub-clause 8.5 part d) of the conditions of particular Application, the Engineer shall not disapprove any document prepared and furnished to him by the Contractor, except on the grounds that the document does not comply with some specified provision(s) of the Contract or that it is contrary to good engineering practice. 5) Circumstances not withstanding, in accordance with the Conditions of Contract, the priority is to ensure that the design and execution of the works is undertaken in accordance with sound and/or good engineering practice. 6) Sub-clause 8.2 and the corresponding Brief Analytical Remarks further reinforces the level of responsibility of the Contractor and in retrospect, the essence and importance of this notifications and/or correspondence regarding all matters related to the Works as well as ensuring adequacy, stability and safety of all site operations and methods of construction. The Contractors liability, obligations and responsibility are limited to

© 2009 Kensetsu Kaihatsu Limited

Page 3

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

8.2

Site operations and methods of construction The Contractor shall take full responsibility for the adequacy, stability and safety of all site operations and methods of construction .provided that the contractor shall not be responsible (except as stated here under or as may be otherwise agreed) for the design or specification of permanent works, or for the design or specification of any temporary works not prepared by the Contractor. Where the contract expressly provides that part of the permanent works shall be designed by the contractor, he shall be fully responsible for that part of such works, notwithstanding any approval by the engineer.

the adherence and observation of the Terms and Conditions of Contract by all Parties concerned. This sub-clause basically qualifies the first paragraph of sub-clause 8.1 above and the corresponding Brief Analytical Remarks It is therefore interpreted that it is imperative for the Contractor to take the initiative, which is commensurate with his responsibilities, liabilities and obligations, to review any documents related to the execution and successful completion of the Works where adequacy, stability and safety factors are upheld in the design and the construction of the Works, failure to which the Contractor is obligated to notify the Engineer and the Employer (Client).

Table 1.2.2 Relevant VE Sub-Clause 13.2 of The Bank Harmonized Edition of the Conditions of Contract – IFCE, FIDIC
13.2 Value Engineering The Contractor may, at any time, submit to the Engineer a written proposal which (in the Contractor’s opinion will, if adopted, (i) accelerate completion, (ii) reduce the cost to the Employer of executing, maintaining or operating the Works, (iii) improve the efficiency or value to the Employer of the completed Works, or (iv) otherwise be of benefit to the Employer. The proposal shall be prepared at the cost of the Contractor and shall include the items listed in SubClause 13.3 [Variation Procedure]. If a proposal, which is approved by the Engineer, includes a change in the design of part of the Permanent Works, then unless otherwise agreed by both Parties: (a) The Contractor shall design this part, (b) Sub-paragraphs (a) to (d) of Sub-Clause 4.1 [Contractor’s General Obligations] shall apply, and (c) If this change results in a reduction in the contract value of this part, the Engineer shall proceed in accordance with Sub-Clause 3.5 [Determinations] to agree or determine a fee, which shall be included in the Contract Price. This fee shall be half (50%) of of the difference between the following amounts: (i) Such reduction in contract value, resulting from the change, excluding adjustments under Sub-Clause 13.7 [Adjustments for Changes in Legislation] and Sub-Clause 13.8 [Adjustments for Changes in Cost], and (ii) The reduction (if any) in the value to the Employer of the varied works, taking account of any reductions in quality, anticipated life or operational efficiencies. However, if amount (i) is less than amount (ii), there shall not be a fee. Value Engineering is basically the development and application of Advanced Technologies aimed at realizing cost-effective, durable, sound engineering and maintenance friendly structure. The Contractor intends to achieve this goal by adopting the State of the Art Technologies developed and widely applied in this region by KKL and introduced in the various sections of this Report. These Technologies have realized between 30 -40% cost savings, whilst further enhancing the Engineering Properties by at least 150 – 300% which culminate in the enhancement of the Structural Capacity, Serviceability Level, Bearing Capacity, Strength and Deformation Resistance of the Pavement Structure.

© 2009 Kensetsu Kaihatsu Limited

1.2.2 Scope of Study and Works The consultants, Kensetsu Kaihatsu Limited were commissioned by the Contractor, Kundan Singh Construction Ltd to undertake a comprehensive geotechnical engineering analysis and review of the original design by employing a Value Engineering (VE) approach and set up State-of-the-Art

Page 4

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

International Standards fostering engineering and scientific concepts that can be tailored and applicable in Songwe, Tanzania. The assignment included but was not limited to the following tasks:i) Review the design using Boeing 747-100 as the design aircraft. ii) Review comprehensively, the original design documents. iii) Study the US Federal Aviation Administration (FAA) Advisory Circular “Airport Pavement Design and Evaluation” AC 150/5320-6D, ICAO Aerodrome Design Manual, Materials and Specifications, ICAO recommended practices as detailed in Annex 14 Volume 1, and any other relevant documents. iv) Undertake comprehensive Site Surveys and Investigations. v) Carry out detailed analyses and assessment of the test data obtained from the tests performed in Tanzania and Kenya. vi) Assessment of the laboratory equipment and capability of the same to carry out material acceptance and pavement control testing. vii) Carry out material investigation, sampling and testing for the proposed runway, taxiway, apron and access roads alignment. viii) Perform tests on any other suitable material sites for aggregate sources, later to be utilized civil works. ix) Carry out geo-material improvement, mechanical, & chemical stabilization and testing for any non-compliance materials and/or for purposes of enhancing the engineering properties of the compliant materials. x) Build capacity in terms of training manpower, and laboratory Technicians on test methods and quality control.

Plate 1.2 Site photo depicting progress and condition of runway pavement and buildings

© 2009 Kensetsu Kaihatsu Limited

1.2.3 Songwe Airport Project and Surrounding Areas Fig. 1.1 shows the roads network of Mbeya region and the link road from Songwe to Mbeya town and surrounding areas, while Fig. 1.2 depicts the satellite imagery of the same.

Page 5

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Fig. 1.1 Lay Out of Mbeya

© 2009 Kensetsu Kaihatsu Limited

Fig. 1.2 Sattellite Image of Songwe Airport in Mbeya Region, Tanzania

1.2.4 Geophysical Details of Songwe Airport in Songwe within Mbeya Region of Tanzania The site for the Songwe Airport located in Mbeya, Mbeya Region, Tanzania, and its geographical coordinates are 9° 41' 60" South, 33° 55' 60" East and its original name (with diacritics) is Songwe.

Page 6

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Airports in Songwe and in the neighbourhood:      Mbeya Airport (distanced approximately 8.2 km) Chitipa Airport (distanced approximately 88 km) Isoka Airport (distanced approximately 170 km) Chelinda Airport (distanced approximately 180 km) East Five Airport (distanced approximately 180 km)

KENYA

TANZANIA

Songwe

Figure 1.3 Sattellite Image of Tanzania (Location of Songwe)

1.3 Relevant Documents and Records Reference is made mainly to the following documents and records.

© 2009 Kensetsu Kaihatsu Limited

1. United Sattes Federal Aviation Administration (US FAA) Advisory Circular No. 150/5320-6D 2. International Civil Aviation Organization (ICAO) Annex 14 Volume I – Aerodrome Design and Operations 3. Aerodrome Design Manual, Part 3 4. Boeing 747-100 Guide to Aerodrome Design and Technical Data 5. The Civil Aviation (Aerodromes) Regulations, 2007 6. AASHTO Guide to Pavement Design 7. Transport Research Laboratory (TRL) Overseas Road Note 31, Berkshire, United Kingdom 8. Japan Road Association Pavemment Design Manual 9. Materials Report and Test Results 10. Construction of Pavements and Buildings at Songwe Airport Contract Documents

Page 7

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

1.4 Brief Background of Project Area The Study including Geotechnical Investigation was carried out for Songwe Airport and the site photos are depicted in Plate 1.3.

Plate 1.3 - Photos Superimposed on Sattelite Imagery showing the Airport

© 2009 Kensetsu Kaihatsu Limited

Location of Songwe in Mbeya - Tanzania. Figure 1.4 – Location map of Songwe in Mbeya Region of Tanzania

Page 8

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Tanzania is located in Eastern Africa between longitude 290 and 410 East. Latitude 10 and 120 South. Tanzania is the biggest of the East Africa countries (i.e. Kenya, Uganda and Tanzania). Has a spectacular landscape of mainly three physiographic regions namely the Islands and the coastal plains to the east; the inland saucer-shaped plateau; and the highlands. The Great Rift Valley that runs from north east of Africa through central Tanzania is another landmark that adds to the scenic view of the country. The rift valley runs to south of Tanzania spliting at Lake Nyasa; one branch runs down beyond Lake Nyasa to Mozambique; and another branch to north-west alongside Burundi, Rwanda, Tanzania and western part of Uganda. The valley is dotted with unique lakes which include Lakes Rukwa, Tanganyika, Nyasa, Kitangiri, Eyasi and Manyara. The uplands include the famous Kipengere, Udzungwa, Matogoro, Livingstone, and the Fipa plateau forming the southern highlands. The Usambara, Pare, Meru, Kilimanjaro, the Ngorongoro Crater and the Oldonyo Lengai, all form the northern highlands. From these highlands and the central saucer plateau flow the drainage system to the Indian ocean, Atlantic ocean, Mediterranean sea and the inland drainage system. Songwe is located south of the Mbeya District in Tanzania.

Mbeya is a city located in southwest Tanzania, Africa. Mbeya's urban population was 280,000 in 2005. Mbeya is the capital of the surrounding rural Mbeya region (population, with Mbeya, totals approx. 2 million). Mbeya is the first large urban settlement encountered when travelling overland from the neighbouring nation of Zambia. Mbeya is situated at an altitude of 1,700m/5500ft, and sprawls through a narrow highland valley surrounded by a bowl of high mountains. The main language is colloquial Swahili, and the English language is extensively taught in schools.

© 2009 Kensetsu Kaihatsu Limited

Fig. 1.5 Map of Mbeya Region Mbeya is one of Tanzania's 26 administrative regions. The regional capital is Mbeya. It is bordered to the northwest by Tabora Region, to the northeast by Singida Region, to the East by Iringa Region, to the South by Zambia and Malawi and to the West by Rukwa Region. According to the 2002 Tanzania National Census, the population of the Mbeya Region was 2,070,046.[1]

Page 9

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

The Mbeya Regions is administratively divided into 8 districts: Chunya, Mbarali, Mbozi, Rungwe, Kyela, Ileje, Mbeya Urban and Mbeya Rural. Following the 1905 gold rush, Mbeya was founded as a gold mining town in the 1920s. The TANZARA railway later attracted farming migrants and small entrepreneurs to the area. Mbeya and its district was administered by the British until 1961. Mbeya Region was created in 1961.

1.4.1 Climate and Vegetation Tanzania has a tropical type of climate. In the highlands, temperatures range between 10ºCand 20ºC.during cold and hot seasons respectively. The rest of the country has temperatures never falling lower than 200c. The hottest period spreads between November and February (25ºC - 31ºC) while the coldest period occurs between May and August (15ºC - 20ºC). Two rainfall regimes exist over Tanzania. One is unimodal (December - April) and the other is bimodal (October -December and March - May). The former is experienced in southern, south-west, central and western parts of the country, and the later is found to the north and northern coast. In the bimodal regime the March - May rains are referred to as the long rains or Masika, whereas the October - December rains are generally known as short rains or Vuli. The general range of temperature is between -6°C in the highlands and 29°C on the lowlands. Mbeya's cooler climate can be deceptive in terms of sun exposure - sun screen lotion is recommended when hiking, even in what seems to be overcast weather. The best weather is from June until October, when it is dry and warm. The area enjoys abundant and reliable rainfall which stimulates abundant agriculture on the rich volcanic soils. Average rainfall per year is around 900mm. The rainy season is from November to May. It is cool and misty in Mbeya much of the time. Sometimes visitors will need warm clothing, such as a sweater or hat, to keep warm. In Tanzania flood prone areas are characterized by high probability of rainfall. Mbeya is one of the flood prone regions of Tanzania including Tanga, Pwani, Morogoro, Arusha, Rukwa, Iringa, Kigoma and Lindi. 1.4.2 General Topographic, Geographic and Existing Conditions The topography varies from flat to rolling, hilly to mountainous landscape. Chunya district is characterized by a hilly landscape (Stretching from Mbeya hills with a gentle slope mostly covering the Kiwanja division) with thick forests, miombo woodlands, scattered trees, bush and thickets. Also the district has flat low lands along lake Rukwa basin; and plateau between Ibagu plains and that of lake Rukwa and Chunya mountain range. The main permanent drainage system include rivers Songwe, Lupa and Zira all originating from Mbeya hills. On the other hand 18 non -permanent rivers (seasonal) exist and mostly flow during rainy season. Commonly known sources of those rivers include Chunya mountain range and Mbeya hills. Along the Project road, the topography raises from Mbeya Municipality (about 1700m) to the highest point of 2457m and characterized with a rolling terrain. Thereafter, the road descend to Chunya town and further to makongolosi (about 1200m).

© 2009 Kensetsu Kaihatsu Limited

Page 10

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

1.5 Geological Formation, Subsoil Conditions and Ground Profile in General

Fig. 1.6 Simplified geological/tectonic map of Tanzania The variety of soils in Tanzania surpasses that of any other country in Africa. Mbeya is characterized by Mainly gently undulating plains, for the most part well drained, at medium altitude, developed on granites and gneisses. Major soils are well drained, moderately deep to deep, red, yellowish red or orange sands and loamy sands with sandy loams in depth, with poor structure and very low natural fertility; and well drained, moderately deep to deep, red or brown, often gravely, sandy loams and sandy clay loams with week structure and low natural fertility; and immature soils which are complexes of rock outcrops, surface ironstone, very stony, and very shallow (< 25cm); and moderately well to imperfectly drained, shallow to deep frequently calcareous, black, dark grey or brown cracking clays often overlying paler subsoil with ephemeral structure and high natural fertility. Soils are generally moderately deep sandy or loamy with low to moderate AWC (30-100mm/m) and poor moisture storing properties mostly for sandy and loamy soils susceptible to surface capping (Smax 50150mm); and favourable for other loamy soils (Smax 150-300mm). In some units with salt affected soils effective soil depth is restricted by impervious subsoil, often high ESP.

© 2009 Kensetsu Kaihatsu Limited

Page 11

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Fig. 1.7 Major Soil Groups of Tanzania

© 2009 Kensetsu Kaihatsu Limited

Page 12

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Fig. 1.8 Soil map of Mbeya region 1.6 Determination of Pavement Structural Design 1.6.1 Determination of Total Pavement Thickness Required Subsequent to determining the Mean-section Design CBR values for the subgrade and the subbase (ref. to table 1.6.1), the weight on the main landing gear was determined from Fig. 7.2.4 in Chapter 7 of this Report. Having pre-determined the design aircraft and the number of annual departures of the design aircraft, the design curves in Fig. 7.2.5 presented in Chapter 7, based on the U.S. Army Corps of Engineers Design Method S-77-1 and the U.S. FAA Design method, the total pavement thickness required wasderived.

© 2009 Kensetsu Kaihatsu Limited

Table 1.6.1 is a summary of the main design parameters that were adopted in determining the total pavement design thickness. Table 1.6.1 Summary of Main Design Parameters Adopted
Design Aircraft Maximum Design Taxi Weight (kgs) 334,800 Weight on Main Landing Gear (kgs) 318,060 Number of Equivalent Annual Departures 3,000 Design CBR (%) Existing Subgrade 50 Existing Subbase 334 Design Life (yrs) Remarks

B747-100

20

Page 13

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Based on the data presented in Table 1.6.1, the Total Pavement Thickness required was detrmined from Fig. 7.2.5 presented in Chapter 7. The Total Pavement Thickness required is 7.4 inches or 188mm. Consequently, the design considers a Total Pavement Thickness of 200mm.

1.6.2 Thickness of Subbase The thickness, bearing capacity, strength and deformation resistance of the existing subbase were technically evaluated (ref. to Chapter 5) and determined to be more than adequate. Due to the coupled effects of cementation and Long Term Consolidation, the existing subbase exhibits very high bearing capacity and strength values (ref. to Section 5.3 of Chapter 5 of this Report). Consequently, 200mm is considered to be the combined thickness of the Base Course and Surface Course.

1.6.3 Thickness of Surface Course The thickness determined in the Original (existing) design of 100mm (40mm Wearing Course + 60mm Binder Course) was technically evaluated and found to be adequate (ref. to Subsection 1.7.1 and 1.7.2 of this Report). This thickness and configuration is therefore maintained as per the Original (Existing) Design.

1.6.4 Thickness of Base Course The thickness of the Base Course was computed by subtracting the thickness of the Surface Course from the combined thickness (i.e. 200-100mm) = 100mm. The required thickness of the Base Course was therefore determined to be 100mm.

1.6.5 Thickness of Non-Critical Areas The total thickness of the original design for the non-critical areas was technically evaluated and found to be adequate (ref. to Chapter 5 of this Report). This thickness and configuration is therefore maintained as per the Original (Existing) Design.

1.6.6 Typical Cross-section

© 2009 Kensetsu Kaihatsu Limited

The Typical Cross-section of the Songwe Airport pavement structure designed in accordance with the U.S. Federal Aviation Administration (FAA) and the International Civil Aviation Organization (ICAO) Design Codes and stipulations is shown in Fig. 1.6.1.

Page 14

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

TOPSOIL AND SEEDING

SHOULDER

RUNWAY

SHOULDER

TOPSOIL AND SEEDING

Fig. 1.6.1 Typical Cross-section based on US FAA / ICAO Design Methods

1.7 Comparison of Various Adequate Designs Under this section, a comparison of various designs that were structurally considered to be adequate for the design aircraft and design life is presented. The main factors employed in undertaking this comparison are Structural Capacity Analysis, deformation Resistance Analysis, Cost and Construction Time Savings.

1.7.1 Comparative Analysis of Structural Capacity

The �������� Method was adopted in computing and analyzing the structural capacity of the composite pavement structure. The value of �������� is calculated from the following equation.
�������� = ����1 ����1 + ����2 ����2 + ⋯ �������� �������� (1.1)

© 2009 Kensetsu Kaihatsu Limited

Where, ����1 , ����2 … �������� = Conversion Coefficient presented in Table 1.7.1. ����1 ����2 … �������� = Thickness of each pavement layer in cm. For a cost effective design for the Songwe Airport, the Target �������� including a global Safety Fator of 1.25 was determined to be (�������� ≅ 30) to cater for a projected Air Traffic for the B747-100 design aircraft and 3,000 Equivalent Annual Departures for a Design Life of 20 Years.

Page 15

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 1.7.1 Conversion Co-efficient for the Calculation of ��������
Pavement Course Method and Material of Construction Surface & Binder course Base Hot asphalt mix for surface and binder course Bituminous Stabilization Hot-mixed stability: 350kgf or more Cold mixed stability 250 kgf or more Cement Stabilization Lime stabilization Unconfined compression strength (7days): 30 kgf/cm
2

Conditions

Standard Coefficient, an

OPMC/GG Coefficient, an(OPMC)

1.00

GlasGRID Reinforced = 1.35

0.80

OPMC Level 10 = 0.94

0.55

8 = 0.86

0.55

OPMC Level 6 = 0.78

Unconfined compression 2 strength (10 days): 10kgf/cm Modified CBR value: 80 or more Modified CBR value: 80 or more Unconfined compression 2 strength (14 days) 12 kgf/cm or more Modified CBR value: 30 or more 20 to 30

0.45

OPMC Level 4 = 0.65: Cement/Lime Combination OPMC Level 2 = 0.58 OPMC Level 6 = 0.78

Crushed stone for mechanical stabilization Slag for mechanical stabilization Hydraulic slag

0.35 0.55

0.55

OPMC Level 6 = 0.78

Sub-base

Crusher-Run, slag, sand, etc

0.25 0.20

OPMC Level 2 = 0.58

Cement stabilization

Unconfined compression strength (7 days): 10kgf/cm
2

0.25

OPMC Level 4 = 0.65: Cement/Lime Combination

(Source: AASHTO, AAAC, Japan Road Association 1989 and XXIIRD PIARC World Road Congress, Paris 2007)

Notes: Conversion coefficients listed in Table 7.8.1 indicate the ratio of the thickness of the pavement by each method and material of construction to the thickness of hot asphalt mix for the binder and the surface courses

© 2009 Kensetsu Kaihatsu Limited

corresponding to the thickness of each material. Thus, the term a n Tn of Equation in 7.1 indicates the corresponding thickness of the n-th layer converted thickness of hot asphalt mix for the binder and surface courses. For example; 1 cm of pavement adopting mechanical stabilization corresponds to 0.35 of pavement adopting the hot asphalt mix method , and a 20cm of pavement using the hot asphalt mix method would therefore be (0.35×20=7). Also note the OPMC conversion Values determined empirically for varying OPMC Stabilization levels published in the XXIIRD PIARC World Road Congress, Paris 2007.

Page 16

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Structural Capacity of ORIGINAL (Existing) Design
TOPSOIL AND SEEDING SHOULDER RUNWAY SHOULDER TOPSOIL AND SEEDING

Fig. 1.7.1 Typical Cross-section of ORIGINAL (Existing) Design
�������� In this case the �������� is computed as: ����1 �������� = 1x10+0.8x15+0.35x15+0.25x20 = 32.25 > 30 [OK]

Structural Capacity of US FAA/ICAO Based Design
TOPSOIL AND SEEDING SHOULDER RUNWAY SHOULDER TOPSOIL AND SEEDING

© 2009 Kensetsu Kaihatsu Limited

Fig. 1.7.2 Typical Cross-section Based on US FAA / ICAO Design Methods
���������������� In this case the �������� is computed as: ���������������� �������� = 1x10+0.78x10+0.65x20 = 30.8 > 30 [OK]

Page 17

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

OPTION1 Structural Capacity of TYPE I PROPOSED Design

TOPSOIL AND SEEDING

SHOULDER

RUNWAY

SHOULDER

TOPSOIL AND SEEDING

Fig. 1.7.3 Typical Cross-section of Type I Proposed Design
����1 In this case the �������� is computed as: ����1 �������� = 1x10+0.78x15+0.78x15+0.65x20 = 46.4 »> 30 [OK]

OPTION2 Structural Capacity of TYPE II PROPOSED Design
TOPSOIL AND SEEDING SHOULDER RUNWAY SHOULDER TOPSOIL AND SEEDING

© 2009 Kensetsu Kaihatsu Limited

Fig. 1.7.4 Typical Cross-section of Type II Proposed Design
����2 In this case the �������� is computed as: ����2 �������� = 1x10+0.78x15+0.65x20 = 34.7 > 30 [OK]

Page 18

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

OPTION3 Structural Capacity of VE BASED Design
TOPSOIL AND SEEDING SHOULDER RUNWAY SHOULDER TOPSOIL AND SEEDING

Fig. 1.7.5 Typical Cross-section of Value Engineering (VE) Based Design In this case, the basic concept is that, owing to the high bearing capacity values that they exhibit, the Subbase is converted into a Base Course layer of 200mm and the Subgrade is converted into a subbase layer of 300mm.
����3 The �������� is therefore computed as: ����3 �������� = 1x10+0.65x20+0.35x30 = 33.5 > 30 [OK]

1.7.2 Comparative Analysis of Deformation Resistance Deformation Resistance is the ability of a founding structure, sub-structure or super-structue to resist the damaging effects imparted upon it under dynamic and/or static loading.

Analyses of the Deformation Resistance were undertaken by adopting empirically determined Elastic Modulus, ���������������� , which is basically defined as the modulus of elasticity within the linear elastic and recoverable range. In order to effectively characterize the deformation resistance of the composite pavement structure with varying layers under loading, the juxtaposed Full Depth Asphalt Concrete and �������� concept was applied. The resulting �������� is therefore computed based on the following equation.
�������� =
�������� �������� ������������ ������������3 + ������������ ������������ 1 1 3 �������� �������� + ������������ ������������ 1 3 �������� �������� + ������������ ������������ 1 3 �������� �������� + +�������� �������� 1 3 �������� �������� + �������� �������� 1 3 1 3

100 − �������� ������������3

© 2009 Kensetsu Kaihatsu Limited

�������� �������� �������� �������� �������� ������������ + ������������ + ������������ + ������������ + �������� + �������� + 100 − ��������

Where all thicknesses are expressed in cm and, ������������ = Thickness of Asphalt Concrete �������� ������������ = Thickness of Asphalt Treated Base Course �������� ������������ = Thickness of Crushed Aggregate Base Course �������� ������������ = Thickness of Cement Treated Base Course �������� �������� = Thickness of Granular Subbase �������� �������� = Thickness of Existing LTC Subbase ������������ = (100-�������� )=Thickness of Subgrade �������� �������� �������� �������� �������� �������� = ������������ + ������������ + ������������ + ������������ + �������� + �������� = Thickness of Pavement

Page 19

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Deformation Resistance of ORIGINAL (Existing) Design The schematic cross-section of the varying layers of the pavement structural configuration of the Original Design is shown in Fig. 1.7.6 below.

������������ =4,419MPa ������������ =4,419MPa �������� ������������ =3,635MPa �������� ������������ =2,872MPa
�������� �������� =2,080 MPa

Fig. 1.7.6 Schematic Cross-section of varying Layers of ORIGINAL (Existing) Design
����1 ��������

= =

10 × 16.41 + 15 × 15.38 + 15 × 14.21 + 20 × 15.38 + 40 × 15.38 100 164.1 + 230.7 + 213.2 + 255.4 + 615.2 100
3 3

3

= 14.79

����1 ∴ �������� =3,233MPa

Deformation Resistance of US FAA/ICAO Based Design The schematic cross-section of the varying layers of the pavement structural configuration of USFAA/ICAO Based Design is shown in Fig. 1.7.7 below.

������������ =4,419MPa ������������ =4,419MPa
�������� ������������ =7,357MPa �������� �������� =5,976 MPa

© 2009 Kensetsu Kaihatsu Limited

Fig. 1.7.7 Schematic Cross-section of varying Layers of US FAA / ICAO Based Design
����2 ��������

=

10 × 16.41 + 10 × 19.45 + 20 × 18.15 + 60 × 15.38 100
3

3

=

164.1 + 194.5 + 363 + 922.8 100
3

= 16.44

����2 ∴ �������� =4,447MPa

Page 20

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

OPTION1 Deformation Resistance of TYPE I PROPOSED Design The schematic cross-section of the varying layers of the pavement structural configuration of OPTION1 Type I Proposed Design is shown in Fig. 1.7.8 below.

������������ =4,419MPa ������������ =4,419MPa �������� ������������ =7,357MPa �������� ������������ =7,357MPa
�������� �������� =2,080 MPa

Fig. 1.7.8 Schematic Cross-section of varying Layers of Type I Proposed Design

����3 �������� =

10 × 16.41 + 15 × 19.45 + 15 × 19.45 + 20 × 18.15 + 40 × 15.38 100
3

3

164.1 + 291.8 + 291.8 + 363 + 615.2 = 100 = 17.26
3

����3 ∴ �������� =5,141MPa

OPTION2 Deformation Resistance of TYPE II PROPOSED Design The schematic cross-section of the varying layers of the pavement structural configuration of OPTION2 Type II Design is shown in Fig. 1.7.9 below.

������������ =4,419MPa ������������ =4,419MPa
�������� ������������ =7,357MPa �������� �������� =5,976MPa

© 2009 Kensetsu Kaihatsu Limited

Fig. 1.7.9 Schematic Cross-section of varying Layers of Type II Design

����6 �������� =

10 × 16.41 + 15 × 19.45 + 20 × 18.15 + 55 × 15.38 100
3

3

164.1 + 291.8 + 363 + 845.9 = 100 = 16.65
3

����6 ∴ �������� =4,614MPa

Page 21

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

OPTION3 Deformation Resistance of VE Based Design The schematic cross-section of the varying layers of the pavement structural configuration of OPTION3 VE Based Design is shown in Fig. 1.7.10 below.

������������ =4,419MPa ������������ =4,419MPa
�������� �������� =5,976MPa

�������� =3,641MPa
Fig. 1.7.10 Schematic Cross-section of varying Layers of Value Engineering (VE) Based Design
����4 ��������

=

10 × 16.41 + 20 × 18.15 + 30 × 15.38 + 40 × 15.38 100
3

3

=

164.1 + 363 + 461.4 + 615.2 100
3

= 16.04

����4 ∴ �������� =4,125MPa

1.7.3 Cost Comparative Analysis A summary of the costs between the Original Design costs and the Reviewed Design costs is presented in Table 1.7.1 for each pavement layer, whilst a graphical representation of the same is depicted in the chart in Fig. 1.7.11. Table 1.7.1 Summary of Comparison of Costs
Construction Costs (TZ, TShs) BoQ Pavement Layer Item No. Without Design Review [ORIGINAL] (1) 1,470,150,000 With Design Review [TYPE I] (2) Difference (3)=(1)-(2) With Design Review [TYPE II] (4) 0 0 0 Difference (5)=(1)-(4) Remarks

103 Crushed Aggregate Base 0 Course (150mm) Runway Crushed Aggregate Base 62,055,000 0 Course (150mm) Taxiway Crushed Aggregate Base 123,750,000 0 Course (150mm) Parking Area Crushed Aggregate Base 129,195,000 0 Course (150mm) Connector Roads 104 Cement Treated Base 0 4,861,350,000 Course for Runway and Taxiway (2×150mm), including Parking Area and Connector Roads 105 Asphalt Trreated Base 5,029,600,000 0 Course (150mm) for Runway and Taxiway TOTAL 6,814,750,000 4,861,350,000

1,470,150,000 62,055,000 123,750,000

1,470,150,000 62,055,000 123,750,000

© 2009 Kensetsu Kaihatsu Limited

129,195,000

0

129,195,000

-4,861,350,000 2,975,250,000

-2,975,250,000

5,029,600,000

0

5,029,600,000

1,953,400,000 2,975,250,000

3,839,500,000

Page 22

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Fig. 1.7.11 Graphical depiction of summarized comparison of Maintenance Costs
Comparison of the ORIGINAL (Existing) Design and the REVIEWED Design Type I indicates that a substantial savings of 29% (TShs1,953,400,000) will be realized by adopting the REVIEWED Design Type I. The computational results further show that the Reviewed Design Type II will culminate in tremendous cost savings of 56% (TShs. 3,839,500,000)

1.7.4 Construction Time Comparative Analysis Comparative analysis of the construction time that would be required is made for the Original (Existing) Design and the Proposed Type I Design. Note that the comparison is made with respect to only the crushing time required for the crushed aggregates quantified in the Original (Existing) Design. A summary of the computations is presented in the tabulation format below. (1) Original Design
Volume of Crushed Aggregate Base Course Material (150mm) for Runway Volume of Crushed Aggregate Base Course Material (150mm) for Taxiway Volume of Crushed Aggregate Base Course Material (150mm) for Parking Area Volume of Crushed Aggregate Base Course Material (150mm) for Connector Roads Volume of Crushed Aggregate for Asphalt Treated Base Course Material (150mm) for Runway and Taxiway Only = 32,670m
3

=

1,379m

3

=

2,750m

3

=

2,871m
3

3

= = = = =

25,148m

© 2009 Kensetsu Kaihatsu Limited

Total Volume of Material Required Weight of Aggregate Required Add 10% for loss Total Weight of Aggregate Assuming a Crushing Rate of 70m /Hr. and crushing time of 12Hrs/Day 3 Tonnage Crushing/Day = 70m x 12Hrs = No. of days required for Crushing
3

64,818m

3

64,818m x 2.5 0.1 178,250 Tons X

3

=162,045 Tons 162,045 = 16,205 Tons

(Approximately 180,000 Tons)

840Tons = 180,000 / 840 = 214 days (7Months)

Page 23

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

(2) Reviewed (Proposed) Design Type I
Volume of Base Course Material to be Proccessed Approximate Rate of Proccessing per Day No. of days required = = = 64,818m 2,500m 65,000m
3

(65,000m )

3

3

3

/2,500m

3

= 26days

Considering logistics and other cirumstancial prevalences, construction of the Reviewed (Proposed) Design Base Courses may take approximately 2Months. As can be noted the Reviewed Designs will realize appreciable savings in construction time mainly in terms of reduction in crushing time. Early completion will certainly be a major cost-benefit component to the Employer and users.

1.7.5 Derivative Comparison (1) Costs From Table 1.7.1 and Fig. 1.7.11 it can be noted as follows:(i) (ii) WITHOUT Design Review [Original Design] is the more expensive than both TYPE I and TYPE II Reviewed Designs. In comparison to WITHOUT Review [Original Design], WITH Type I Reviewed Design cost savings of TShs TShs1,953,400,000/= (approx. 1.9B) are realized, while WITH Type II Reviewed Design cost savings of TShs 3,839,500,000/= (approx. 3.8B) are made.

(2) Structural Capacity Table 1.7.2 presents a comparison of the structural capacity levels of the various designs.

Table 1.7.2 Structural Capacities based on �������� Values for varying Designs (Target �������� Value = 30)
Original (Existing) Design 32.25 USFAA/ICAO Design OPTION1 Type I Proposed Design 46.4 OPTION2 Type II Proposed Design 34.7 OPTION3 VE Based Design Remarks

30.8

33.5

© 2009 Kensetsu Kaihatsu Limited

Based on the computations made in Sub-section 1.7.1, it can be noted that the Proposed Designs (both Type I and Type II) exhibit the highest Structural Capacity.

(3) Deformation Resistance A comparison of the Deformation Resistance of varying Designs is given in Table 1.7.3.

Page 24

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 1.7.3 Comparison of Deformation Resistance Based on Elastic Modulus for Varying Designs
ORIGINAL (Existing) Design 3,233 USFAA/ICAO Design OPTION1 Type I Proposed Design 5,141 OPTION2 Type II Proposed Design 4,614 OPTION3 VE Based Design Remarks

4,447

4,125

The analysis carried out in Sub-section 1.7.2 which are summarized in Table 1.7.3 indicate that, in comparison to the Original (Existing) Design, the Proposed (Reviewed) Designs enhance the Deformation Resistance by tremendously. It can be noted that, in terms of Deformation Resistance, Type I proposed design is superior to the Original (Existing) Design by 59%, while Type II proposed design exceeds the Original by 43%. This is attributable mainly to the cementatious nature of the Base Course material proposed.

(4) Construction Time This is computationally demonstrated in Sub-section 1.7.4.

1.7.6 Comparative Conclusions In undertaking the foregoing analysis, the impact of environmental factors was taken into consideration (ref. to Chapter 4). It can be noted that not only do both Type I and Type II Proposed (Reviewed) Designs realize enormous Cost-savings but they also enhance the Structural Capacity (Bearing Capacity, Strength, Serviceability) and Deformation Resistance of the Pavement Structure. It can also be noted that these Designs can be implemented within a very short period (Approx. 70% less construction time) in comparison to the Original (Existing) Design.

© 2009 Kensetsu Kaihatsu Limited

Page 25

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

CHAPTER 2 2. BASIC SAMPLING AND SURVEY PROCEDURES IN BRIEF 2.1 Preliminary Field Survey Continuous sampling was undertaken for more than one year between September 9th 2008 and August 23rd 2009. The general site condition assessment was carried out visually, through datum location, GPS recordings, trenching, shallow soil profile examination by pit excavation and basic soil characteristic evaluation. Some representative observations of the Sampling Survey are presented in Table 2.1. Table 2.1 –Soil sampling from Designated Locations of Runway Alignment, Excavated Backslopes and Cut Sections Sampling Location 1 2 3 4 5 6 7 8 9 10 11 Km 2+000 CL Km 2+000 RHS Km 2+100 RHS Km 2+100 LHS Km 2+200 RHS Km 2+200 LHS Km 2+300 LHS Km 2+300 RHS Km 2+400 LHS Km 2+400 RHS Km 2+200 LHS Material Description Pozzolanic Pozzolanic Pozzolanic Pozzolanic Pozzolanic Pozzolanic Pozzolanic Pozzolanic Pozzolanic Pozzolanic Pozzolanic Depth /Source Sampled 0.2m ~ 0.4m 0.2m ~ 0.5m 0.2m ~ 0.5m 0.2m ~ 0.4m 0.2m ~ 0.4m 0.2m ~ 0.4m 0.2m ~ 0.4m 0.2m ~ 0.7m 0.2m ~ 0.4m 0.2m ~ 0.6m Stock Pile/Excavated Backslopes & Cut Sections No. of Samples >20 >20 >20 >20 >20 >20 >20 >20 >20 >20 >120 Laye of Utilization Subbase/Base Course Subbase/Base Course Subbase/Base Course Subbase/Base Course Subbase/Base Course Subbase/Base Course Subbase/Base Course Subbase/Base Course Subbase/Base Course Subbase/Base Course Subbase/Base Course

From the preliminary field observations and material classification, it was concluded that the existing soils provide adequate bearing pressures, capacity, strengths and deformation resistance for subgrade ground necessary to bear the road pavement structure even under certain varying moisture~suction conditions. 2.2 Basic Sampling Regime The basic sampling of disturbed soil samples was undertaken as follows: a) Disturbed soil samples were sampled at every 20 centimetres for confirmation of uniformity and at every 100 metres for laboratory testing from the boreholes at each of the 10 locations. b) The geomaterial samples were immediately transferred to water proof polythene bags in order to preserve the moisture content as much as possible. c) The samples were then sealed properly, tied and appropriately labeled. Details of soil strata encountered at each sampling location were recorded accordingly prior to sending them to the respective Materials Testing Laboratories.

© 2009 Kensetsu Kaihatsu Limited

Geological and Soil Survey Geological and soil surveys mainly associated with the stability of the foundation ground in relation to the original ground prior to cutting, studying the conditions of weathering, strike and inclination of stratum, and the properties of joints and cracks of the existing rock were out of the scope of this Study.

Page 26

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

As a consequence, the shape and size of geomaterials, the conditions of matrix, the geological properties of the soil masses, soil mechanical characteristics of the problematic soils, and the geological characteristics of the ground were not critically examined. Groundwater Survey in General The stability of the ground decreases due to seepage of water whereby drastic reduction in bearing capacity and deformation resistance tending to failure can occur easily. In order to effectively carryout analysis on the characteristics of the generating mechanisms and the degree of extent of damage it causes to the stability of the foundation ground, it is considered vital to determine the groundwater conditions within and around the possible failure zone locationconstituting of location of groundwater – flowing layer, fluctuation in water level, flow of groundwater, runoff path, current speed, quality and temperature of groundwater as well as variation of these factors with seasonal changes. The failure zone motion characteristics and the generating mechanisms can effectively be examined by correlating the hydrological data and groundwater levels. Observations of the seasonal fluctuations in relation to the vegetation in the Project area for purposes of studying the distribution of groundwater zone in comparison to the results of the field survey, are also vital. For purposes of vertically surveying and analyzing the location of groundwater-flowing layer vis a vis the flow conditions, water contents are to be determined for the varying layers of the borelogs. 2.5 Ground Movement Survey in General Ground movement survey is to be predominantly carried out by assessing and evaluating the general stratigraphic column for purposes of examining the scale, direction of movement, and the generating mechanisms of the failure in detail since slight cracks due to inhomogenity had been observed in some cases.

© 2009 Kensetsu Kaihatsu Limited

Page 27

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

CHAPTER 3 3. TESTING, INVESTIGATION AND ANALYTICAL REGIMES 3.1 Design Criteria of Testing, Investigation and Analytical Regimes 3.1.1 Preamble Ground stability of reconstituted foundations may deteriorate with time and seasonal changes depending on both static and dynamic mechanisms and magnitude of the external loads imposed as well as response of the internal stresses. Furthermore, external forces not taken into account at the time of construction may begin to act and result in deformation of the foundation ground. Also, changes in the terrain due to other development activities within the vicinity may sometimes induce instability of the ground. Consequently, the detection of changes that may cause failures and implementation of the appropriate countermeasures forms the fundamental basis the choice and/or design of the testing and investigation regimes adopted.

3.1.2Postulated Failure Mechanism of Pavement and Subgrade Layers Based on Case Study Analysis of in-situ ground behavior as well as field and laboratory data within the East African Region, it is considered that, for the layers overlaying rock and located within shallow depths, failure may predominantly be prompted by rapid moisture~suction variation and the combined components of dynamic loading and pore pressure increase effects. These effects may then culminate in the states briefly summarized here below for the respective layers. (1) Expansive Overburden Soil Layers This would result mainly in the reduction of density, bearing capacity, strength and deformation resistance primarily as a result of decrease in angle of shearing resistance and shearing stress. (2) Lower Sandy Clayey Layers Crack propagation at the joint within the lower sandy clay layers may occur mainly due to the reduction in confining stress as a result of increased pore water pressure combined with the effects of dynamic loading due to traffic. The shear failure planes and differential settlement measured and observed during most case studies indicate that the failure tendency may propagate towards a critical state as excitement due to dynamic loading increases. (3) Main Objectives of Regimes Design and/or Choice Criteria Adopted In general, the regimes were designed and developed in order to determine appropriate design measures by establishing the following. Effectively assess and evaluate the field conditions including the propensity of ground failure motion and behaviour, failure mechanisms and the direction and rate of failure where possible. (b) Correlate as comprehensively as possible, the failure mechanisms due to changes in environmental factors. (c) Estimate groundwater-flowing layer and the flow conditions as precisely as possible. (d) Examine the scale, direction of movement and generating mechanisms of the possible failure zone. (e) Determine the necessary engineering parameters to determine a cost-effective and value Engineering (VE) based foundation and structural design. (f) Predict as precisely as possible, future failure or stability mechanisms. (g) Predict future structural performance and design life of the ground performance and foundation structure. (h) Propose effective methods of maintenance including emergency countermeasures for future protection works. However, it is important to note that items (c) ~ (h) are out of scope of this Report. (a)

© 2009 Kensetsu Kaihatsu Limited

Page 28

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

3.2 In-Situ and Laboratory Testing 3.2.1 Determination of Basic In-Situ Material Properties Conventional testing techniques were applied to determine some basic physical properties of the in- situ materials sample from the boreholes. In-situ natural moisture content, Atterberg Limits, sieve analysis measurements and sieve analysis were carried out for the varying layers for disturbed samples extruded from the respective boreholes.

3.2.2

Brief Introduction of In-situ and Laboratory Tests Undertaken (1) Laboratory Tests The laboratory tests performed included Atterberg Limits, Specific Gravity, Dry and Bulk Density Sieve Analysis and measurement of Natural Water Content. (2) In-situ Tests The in-situ tests undertaken included measurement of Drilling Resistance, Soil Classification, Dynamic Cone Penetration Test (DCPT) and Geophysical Survey by conducting Geo-electric Prospecting.

3.3 Summary of Laboratory Methods of Testing The laboratory tests were performed on proposed materials under close supervision at the laboratory. All laboratory tests were performed in accordance with the Standards presented in Table 3.1. The analyzed test results are presented under sub-section 5.1 of Chapter 5 of this Report.

3.3.1 Specific Gravity Specific gravity tests were conducted in accordance with AASHTO T-100, on representative samples of course aggregate. A sample of aggregate is immersed for 24 ± 4 h to essentially fill the pores. It is then removed from water, the water dried from the surface of the particles, and the mass determined. Subsequently, the volume of the sample is determined by the displacement of water method. Finally, the sample is oven-dried and the mass determined.

3.3.2

Atterberg Limits

© 2009 Kensetsu Kaihatsu Limited

Atterberg limits were performed in accordance with AASHTO T-89/T-90, on soil samples. The liquid limit was determined by Casagrande cup method and the plastic limits were determined via “Rolling- Thread” method. For liquid limit determination, four water contents with blow counts between 15 and 35 were adopted. As for plastic limit, two (2) measurements were made. The tests data are compiled in Appendix A.

3.3.3

Sieve Analysis

Sieving was conducted in accordance with AASHTO T-27/T-28, to determine the percentage of coarse and fine-grained material. A small but representative soil sample is allowed to be dried in the oven at 110oC for a period of 24 hours. The dry soil is weighed and washed through No. 200 sieve (75 and then m), the soil retained is collected and oven-dried. After drying, the soil is sieved through No. 2” to No. 200 sieves. The proportion of soil retained on each sieve is noted, and the grain size distribution curve is plotted together with hydrometer test results.

Page 29

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

3.3.4

Natural Water Content

Three small but representative soil samples are selected from various locations of the water proof polythene bags, weighed to determine the moist weight and allowed to be dried in the oven at 110 for a C period of 24 hours. Subsequently, the samples are weighed to determine the dry weight. The difference between the moist and dry weights is then computed and presented in percentage form. This test was basically conducted in accordance with JIS A1203.

3.4 Summary of In-situ Methods of Testing The in-situ tests were performed in the field under close supervision. All in-situ tests were performed in accordance with the Standards presented in Table 3.2. The analyzed test results are presented under sub-sections 5.2 ~ 5.10 of Chapter 5 of this Report.

3.4.1

Dynamic Cone Penetration Test

In geotechnical and foundation engineering, in-situ penetration tests have been widely used for site investigation in support of analysis and design. The Standard Penetration Test (SPT) and the Cone Penetration Test (CPT) are two typical in-situ penetration tests. While SPT is performed by driving a sampler into the soil with hammer blow, the CPT is a quasi-static procedure. Fundamentally, the Dynamic Cone Penetration Test (DCPT) exhibits features of both the CPT and SPT. The DCPT is performed by dropping a hammer from a certain fall height measuring penetration depth per blow for a certain depth. As a consequence, it is quite similar to the procedure of obtaining the blow count N using the soil sampler in the SPT. In the DCPT, however, a cone is used to obtain the penetration depth instead of using the split spoon soil sampler. In this respect, there is some resemblance with the CPT in the fact that both tests create a cavity during penetration and generate a cavity expansion resistance. The DCP basically consists of upper and lower shafts. The upper shaft has an 8 kg (17.6 lb) drop hammer with a 575 mm (22.6 in) drop height and is attached to the lower shaft through the anvil. The lower shaft contains an anvil and a cone attached at the end of the shaft. The cone is replaceable and has a 60 degree cone angle. As a reading device, an additional rod is used asan attachment to the lower shaft In order to run the DCPT, two operators are required. One person drops the hammer and the other records measurements. The first step of the test is to put the cone tip on the testing surface. The lower shaft containing the cone moves independently from the reading rod sitting on the testing surface throughout the test. The initial reading is not usually equal to 0 due to the disturbed loose state of the ground surface and the self-weight of the testing equipment. The value of the initial reading is counted as initial penetration corresponding to zer blow.

© 2009 Kensetsu Kaihatsu Limited

Page 30

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Plate 3.1 Checking DCPT Equipment and DCP Testing at location site The penetration rate was determined as a function of the bearing ground resistance and the results were correlated directly with SPT blow count, CBR and UCS.

3.5 Schedule and Summary of Tests Performed 3.5.1 Laboratory Tests Samples obtained from the material sites were tested in the laboratory considering the following basic objectives.  Compaction Tests To be undertaken for the basic purposes of: Specifying a suitable Design Moisture Content for field compaction.  Specifying a minimum Dry Density to be obtained in the field.  Determining the Moisture Content to be employed in moulding compressive strength and CBR specimens. Compressive Strength (UCS) and CBR Tests To be undertaken with the basic objective of: Determining the suitability of the soil for treatment and comparing different mixtures.  Specifying the appropriate cement content to be used in the construction.  Provide a standard by which the quality of the field processing can be assessed. Durability Tests These tests will be carried out specifically for:  Determining the suitability and extent of stabilization particularly for the subbase and base course material.  Investigate the suitability of stabilized soil for use under particularly severe environmental and dynamic loading conditions.





© 2009 Kensetsu Kaihatsu Limited

(1)

Conditions of Moulding a.    Type of Materials In-situ base course material In-situ subbase material In-situ subgrade material

Page 31

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

b.

Type of Treatment Cement treatment for base course, in-situ base course, and in-situ subbase. Depending on the test results, the in-situ subgrade may be treated by both lime and cement or either.

Cement and/or Lime Content  All material to be tested: 0, 1, 2, 3, 4, and 6% by weight for both UCS Tests and CBR Tests.  Where both cement and lime are combined, the Cement to Lime ratio shall be 70:30 % by weight or unless as determined from Laboratory tests.

(2)

Number of Samples

A minimum of 3 No. samples for each testing condition was adopted.

(3)

Modes of Curing

The modes of curing indicated below should basically be adopted for experimental purposes of determining the most appropriate mode that is suitable for the geomaterial to be tested.
3 days cure under moist conditions Compressive strength or CBR Tests

One day soak

4 days cure under moist conditions

Zero days soak (Unsoaked)

Compressive strength or CBR Tests

Seven days cure under moist conditions Six days cure under moist condition

Seven days soak

Compressive strength or CBR Tests

One day soak

Compressive strength or CBR Tests

© 2009 Kensetsu Kaihatsu Limited

Seven days cure under moist conditions

Zero days soak (Unsoaked)

Compressive strength or CBR Tests

(4)

Method of Testing  Strength Tests

Preparation of specimens and testing for strength shall basically be conducted in accordance with BS 1924 (1990) or ASTM D558-82 (Reapproved 1990) with some modifications to be determined in relation to the actual prevailing field conditions.

Page 32

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009



Basic Method of Sample Preparation

Mix cement and material thoroughly at designated percentage ratio of dry weight of material i.e. final cement content, density and
d CC = d C Cf   s  d  C C

where

C Cf

=

designated cement content,

 S = wet

 d = dry density

To simulate field conditions of mixing leave the mixed material for at least 30 minutes but not longer than one hour prior to compaction.

Compact the material applying the standard method to a final OMCf which should be greater than the pre-determined OMCP by 10% i.e. OMCf = 1.1xOMCP (approximately).

Cure the sample under moist and moulded conditions for the designated curing period.

Soak the samples for the designated period of soaking.

Carryout the CBR or UCS strength tests accordingly

© 2009 Kensetsu Kaihatsu Limited

Page 33

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

 Durability Tests In-order to better simulate the etreme environmental and loading conditions on the Airport Pavement Structure, the durability tests will basically be modified as follows.

Mold the specimens in the concrete or CBR moulds in accordance with the standard

specifications. Cure the test specimens under moist conditions for a period of 7 days, weigh and measure.

Place in a 1100C oven for 3 hrs or in a microwave oven for a period calibrated to ensure similar amount of loss in moisture content.

Remove the specimens weigh, measure and compute MC.

Firmly brush each face of the sample with a stiff wire brush giving two strokes to each face.

Weigh the samples again and record the percent loss of the sample resulting from the brushing.

Repeat Steps 3 ~ 6 until the specimens have undergone 12 cycles

© 2009 Kensetsu Kaihatsu Limited

Page 34

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

 Schedule of Tests

Table 3.5.1. Standard Tests for Soils and Gravels
Description of Test Equivalent Standard/ Specification commonly used in East African Region AASHTO T-89/T-90 AASHTO T-91 AASHTO T-100 AASHTO T-27 AASHTO T-28 AASHTO T-84 ASTM-1411 ASTM-C289 AASHTO T-99 AASHTO T-180 BS598 Part 104 (1989) AASHTO T-193 A1121 A1210 A1211 JIS Equivalent Standard/ Specification A1203 A1205/6 A1209 A1202 A1102 A1103 A1202 No. of Tests Remarks Recommended 102 34 4 17 17 17 2 17 17 27 specialized Innovative tests only

Moisture Content Atterberg limits Determination of linear shrinkage Determination of specific gravity of particles Particle size distribution to 0.075mm (dry sieving) Determination of particle size distribution to 0.075mm (wet sieving) Hydrometer analysis for finegrained soils Organic matter content Total sulphate content pH value Density-moisture relationship (2.5kg rammer – AASHTO T99) Density-moisture relationship (4.5kg rammer – AASHTO T180) Density-moisture relationship (Vibrating Hammer) CBR of specimen statically compacted to 100% MDD & OMC at 4 days soak CBR at 95% MDD (MOD. AASHTO) of specimens dynamically compacted at 3 levels of compaction & OMC at 4 days soak Sand equivalent Field density (sand replacement method) Triaxial Testing (CUTC)

AASHTO T-194 AASHTO T-176 AASHTO T-191 Innovated

A1122

27 -

A1214

-

© 2009 Kensetsu Kaihatsu Limited

Notes i. ii. iii. Innovative and In-situ Tests to be determined during the Study and charged from the Contingency Account. Tests to be carried out in Mbeya, Dar Es Salaam or Nairobi unless otherwise all testing facilities are available on site. Highly qualified Staff to be assigned for undertaking the tests

Page 35

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 3.5.2: Standard Tests for Aggregate, Sand & Filler
Description of Test Equivalent Standard/ Specification commonly used in East African Region AASHTO T-27 AASHTO T-112 BS812 Part 105 (1989) ASTM D-2049 BS812 : Part 110 1990 BS812 Part 117 (1988) AASHTO T-96 AASHTO T-104 BS812 Part 1 (1975) BS812 Part 110 JIS Equivalent Standard/ Specification A1204 A1126 No. of Tests Remarks Recommended 30 30 30 30 30 30 30 30 -

Determination of particle size distribution to 0.075mm (ISO sieves) Clay, silt and dust in fine or coarse aggregate Flakiness index Relative density and water absorption Bulk density, voids and bulking Aggregate crushing value (ACV) Soluble chloride content Los Angeles Abrasion Value (LAA) Sodium or magnesium sulphate soundness Average least dimension (ALD) of aggregate Crushing ratio (CR of aggregate)

Table 3.5.3: Standard Tests for Cemented Materials
Description of Test Equivalent Standard/ Specification commonly used in East African Region AASHTO T-99 AASHTO T-190 AASHTO T-99/T-180 BS1924 : 1990 AASHTO T-134/T-208 BS 1377 (1990) Part 8 AASHTO T-134/T-208 BS 1377 (1990) Part 8 AASHTO T-193 4 4 4 17 A1216 A1216 A1121 JIS Equivalent Standard/ Specification No. of Tests Remarks Recommended 34 34 34 34 17 17

© 2009 Kensetsu Kaihatsu Limited

Density – moisture relationship (2.5 kg rammer – AASHTO T99) Density – moisture relationship (4.5 kg rammer – AASHTO T180) Density – moisture relationship (V.H) Determination of the Unconfined Compression Strength (UCS) Effect of immersion in water on the UCS CBR at 95% MDD (MOD. AASHTO) of specimens dynamically compacted at 3 levels of compaction & OMC at 7DC + 7DS Cement content of cement treated material Lime content of lime treated material Initial consumption of lime (ICL) Durability Tests

NITRR (1984) BS 1924 : 1990 BS 1924 : 1990 BS 1377 : 1990 Part 5

Page 36

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

2.

Durability Tests

Table 3.5.4 Conditions of Testing for Durability Tests
Conditions of Testing Type of Tests Wetting/ Drying Cycles Material Type 1 Variation in Cement Content 3 Modes of Curing 1 No. of Samples 3 Total No. of Tests 9

3.5.2

In-situ Tests

The in-situ tests undertaken in the field are summarized in the schedule presented in Table 3.5.5.

Table 3.5.5: Schedule of Standard In-situ Tests
Description of Test Equivalent Standard/ Specification commonly used in East Africa region ASTM D1586 BS 5930 TRRL (1990) JIS Equivalent Standard/ Specification No. of Tests recommended Remarks

Drilling Soil classification Disturbed sampling Dynamic Cone Penetration Geophysical survey

A1219 A1205/6

0 >36 >36 >34 0

© 2009 Kensetsu Kaihatsu Limited

Page 37

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

CHAPTER 4 4 RELEVANT ENGINEERING CONCEPTS AND THEORIES APPLIED This Chapter presents the relevant fundamental engineering concepts and theories that were applied in carrying out the data analyses. Several State of the Art analytical tools developed on the basis of innovation and long-term research form the basis of methods applied for analyzing the results presented in Chapter 5.

4.1 Outline of Methodology of Data Analysis, Evaluation and Criteria for Suitability Data analysis, evaluation and subsequent establishment of appropriate design criteria, method of construction and desirable field quality control techniques is to be established on the basis of precise analytical tools based on recently developed research oriented quasi-empirical relations on foundation engineering and construction. This should be undertaken with the concise objective of enhancing the precision of the methodology adopted.

4.2 Determination of Basic Parameters 4.2.1 Standard Soil Model Expressions

In order to establish the magnitude of change of the physical properties of the existing foundation geomaterials and their corresponding effects on the bearimg capacity, strength, moduli of deformation, basic parameters such as natural moisture content (wn), Atterberg Limits (PI, LL, WL, & LS), Specific Gravity (Gs), voids ratio (e), dry density (d) and degree of saturation (Sr) were determined based on the standard soil model expressions. In general terms, plasticity index is a function of the amount of clay present in a soil, while the Liquid Limit and Plastic Limits individually are functions of both the amount and type of clay. High plasticity indices are analogous to high water contents whose lubricating effect of the water films between adjacent soil particles tends to reduce the mechanical stability, strength and deformation resistance. This phenomenon is quantitatively illustrated by the following generalized empirical equations.

 q    mc  u vmc    q PI   q  qu imc   E    mc  50 vmc    EUPI   EU  E50 imc 

(4.1)

(4.2)

© 2009 Kensetsu Kaihatsu Limited

 E    mc  max vmc    EmPI   Em  Emax imc 
where,

(4.3)

mc = γmcMcu/Mci (Moisture Content Variation Factor),
umc=Ultimate Moisture Content, imc=Initial Moisture Content, and,

Page 38

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

γmc = 0.53 for expansive soils such as black cotton = 0.35 for natural gravels and lateritic materials = 0.28 for OPMC Stabilized materials

q u = Peak strength determined from Unconfined Compression (UCS) Tests,
E50 = Pre-failure modulus determined from UCS or CUTC tests,

Em ax = maximum Youngs Modulus,
PI = Plasticity Index,

 q = -0.0123,  EU = -0185,  Em = -0.0362 and  q = 0.535,  EU = 0.823,  EU = 1.9 are material
constants related to strength, pre-failure and Young’s modulus respectively. Substituting for q u in Equation 4.1 from the relation between UCS and CBR in Equations 4.20 and 4.21, we obtain,

  CBR   gl     1    f OPMC   gi  umc      mc     q PI   q (%)    CBR   gl  1     f OPMC    gi  imc    

(4.4)

The following empirical formula that correlates the bearing capacity expressed in terms of CBR and the Plasticity Index is also employed.


Where,

gi

  gl PI  BC

 CBRm  35
(%) 4.5)

 gi = 0.97,  gl = 0.027 and  BC = 0.564 being the gradient linear, gradient intercept and Bearing
Capacity materials constant of most tropical geomaterials tested and, CBRm is the measured CBR value obtained at a density corresponding to 95% MDD in accordance to AASHTO T180 Method D for various soaking and curing periods.

© 2009 Kensetsu Kaihatsu Limited

Substituting for q u from Equation in Equation 4.1, we obtain Equation 4.6 as follows,

  gl ln CBR   gi umc    mc     q PI   q (%)   gl ln CBR   gi imc   
Where,

(4.6)

 gl = 12.9, and  gi = 36.5 being the gradient logarithimic, and gradient intercept materials constants
for most geomaterials tested.

Page 39

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

4.2.2

Concepts Applied for Analyzing Impact of Environmental Factors

Environmental factors are known to highly affect the concepts of design, actual construction and ultimate performance of civil engineering structures. In this study, some comprehensive methods that may be effective for evaluating the impact of these factors are proposed. A new concept of evaluating the deterioration of the structural thickness as a result of infiltration of underlying material to the upper layers is also introduced. Application of these concepts and methods show that the impact of environmental factors over a given period of time can be more detrimental than commonly considered in most cases The main objective of undertaking this research therefore was to develop new quantitative analytical concepts and methods of effectively evaluating the impact of environmental factors such as geology, topography and climate (seasonal changes) on the performance of civil engineering structures. The major environmental factors considered which highly depend on topograghic, geographical, geological, climatic and other changes are depicted as follows:



Effect of Swelling

Recent research has shown that for most geomaterials, swell can be contained by applying a surcharge pressure of approximately 24KPa as can be derived from Equation (4.7).

 sc  sc ln  sc   sc
Where,

(%)

(4.7)

 sc  Swell in relation to surcharge pressure

 sc  12.9; logarithmic gradient constant for standard tropical geomaterials  sc  Surcharge Pressure in Kpa
 sc  36.5; logarithmic intercept constant for standard tropical geomaterials



Effect of Variation In Design Moisture Content

The selection of an appropriate design moisture content and density condition is critical to the design analysis and subsequent construction Quality Control. The moisture content at which overlying layers strength should be assessed is that which can be expected to be exceeded only rarely. Pronounced exceedance of this factor is known to have adverse effects on the foundation structure.

© 2009 Kensetsu Kaihatsu Limited

 DMC   gl ln PI   gl
Where,

(4.8)

 DMC  Design Moisture Content Ratio
 gl  0.12; logarithimic DMC gradient constant for tropical geomaterials
PI  Plasticity Index of the geomaterial to be utilized for construction

 gi  0.7; logarithimic DMC intercept constant for tropical geomaterials
Correction factors for the Plasticity Indices and the Design Moisture Contents respectively, during the wet and dry seasons are defined in the following relations.

Page 40

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

PI d  Ap e Bp PI w
Where,

(4.9)

A p = 12; linear gradient constant for PI for tropical geomaterials

PI d  Plasticity Index of the geomaterial during the dry season
e Bp  Annual Evapotranspiration Factor
BP = 0.02; Exponetial constant for PI for tropical geomaterials

PI w  Plasticity Index of the geomaterial during the wet season
D w mc  Am e Bm D d mc
Where, (4.10)

Am = 0.97; linear gradient constant for DMC for tropical geomaterials
D w mc  Design Moisture Content of the geomaterial during the dry season
e BM  Annual Evapotranspiration Factor
Bm = 0.03; Exponetial constant for DMC tropical geomaterials

D d mc  Design Moisture Content of the geomaterial during the wet season


Seasonal Effects On Bearing Capacity and Resilient Modulus The combined effects of seasonal changes and soaking conditions on the bearing capacity and resielent modulus of some geomaterials is presented in Equations (4.11) ~ (4.13).

wdr   gl ln CBR w   gi
Where,

(4.11)

wdr = Wet to Dry Season Bearing Strength Ratio
 gl = 0.0022; logarithimic CBR gradient constant for tropical geomaterials  gi = 0.54; logarithimic CBR intercept constant for tropical geomaterials
The relation between the CBR wet and dry season ratio vs. the CBR determined during the dry season is correlated as follows.

© 2009 Kensetsu Kaihatsu Limited

ddr   gl ln CBR d   gi
Where,

(4.12)

wdr = Wet to Dry Season Bearing Strength Ratio
 gl = 0.0022; logarithimic CBR gradient constant for tropical geomaterials  gi = 0.54; logarithimic CBR intercept constant for tropical geomaterials

 wMr   gl ln M r   gi

(4.13)

Page 41

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Where,

 wMr = Wet to Dry Season Resilient Modulus (Mr ) Ratio
 gl = 0.0022; logarithimic Mr gradient constant for tropical geomaterials

 gi = 0.54; logarithimic Mr intercept constant for tropical geomaterials

4.3 Bearing Capacity Analysis 4.3.1 Derivation of Correlations of N-value, UCS and CBR

Lacroix and Horn (1973) proposed that Non-Standard Penetration Resistance, NNS, could be correlated with the Standard Penetration Resistance, NSPT, for drive samples or solid conical point apparatus such as the DCP, static cone etc., which incorporated consideration of driving energy and distance of penetration. Their reasoning was that the energy required to drive the sampler or cone through a given distance or depth (d) was directly proportional to the square of the external diameter (De) and the distance of penetration, and inversely propotional to the energy per blow {Weight of hammer (Wh ) multiplied by the height of drop (Hd)}, whence: NSPT = NNS {D2/Di}2 × D12/d × Wh/W140 × Hd/D30 = Where, D2 = 50mm, D12 = 300mm, W140 = 65kg and D30 = 76mm On the other hand, Skempton, 1986, proposed that SPT data can be corrected for a number of site specific factors such as type of geomaterial, overburden pressure, relative density, particle size, aging and overconsolidation in order to account for efficiency and improve its repeatability, as well as precision. In this publication, the procedures for determining a standardized blowcount were presented, which allow for hammers of varying efficiency to be accounted for. This corrected value is usually reffered to as N60, since the original SPT (Mohr) hammer has about 60% efficiency, and this is the so termed “standard” to which other blowcount values are compared. The SPT N-value corrected for field procedures and apparatus, N60, is therefore given as: N60 =
E mN C B C R C S fR ����× ������������ �������� �������� ����×�������� ����

(4.14)

(4.15)

Where,

© 2009 Kensetsu Kaihatsu Limited

�������� =������������������������

���������������������������������������� , ����= ������������ ����−�������������������� ,

�������� = �������������������������������� �������������������������������� ����������������������������������������, �������� = ������������ ������������������������ ����������������������������������������, �������� = ������������������������ ������������������������ ����������������������������������������, ��������= 0.6 On the other hand, comprehensive research undertaken over the past decade has developed empirical equations based on field and laboratory data for tropical soils within the East and Central African Region that correlate the SPT N-value and the Unconfined Compression Strength (qu) expressed as: NSPT = ANf qu + BNf where, (4.16)

Page 42

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

���������������� = ������������ ���� − ��������������������, �������� = ���������������������������������������� �������������������������������������������� �������������������������������� (������������/��������2 , = 0.3 ������������ �������������������������������������������������������� ���������������������������������������� �������������������������������� ������������������������������������.

������������ = 1.93, ������������ ������������

Based on the foregoing and various other correlations, Mukabi et al. (2004, 2006 and 2007), established empirical relations equating the SPT N-value (���������������� ), �������� , and ������������ , to the inverse of the rate of penetration −1 �������� (��������/����������������), determined from Dynamic Cone Penetration Tests (DCPT) as follows:
−1 NSPT = ANv × PR −1 q u = Aqu × PR −1 CBR = ACBR × PR

(4.17) (4.18) (4.19)

Where, ������������ = 150, ������������ = 73.4, ���������������� = 304 ������������ ������������������������������������������������ ������������������������������������.

4.3.2

Derivation of CBR and qu Relations for Stiff Geomaterials

An empirical formula relating the bearing capacity based on CBR for materials where CBR ≥ 50, and Unconfined Compression Strength (UCS) is defined as:

CBR  { gl q u   gi }  f OPMC

(%)

(4.20)

Rewriting Equation (4.20) we obtain,

 CBR   gl    qu    f  gi    
where,

1

OPMC

(kgf/cm2)

(4.21)

λgl = 14.4 and λgi = 46.6 being the gradient linear and gradient intercept of most geomaterials tested in the 2001 Study and,
s f OPMC  f opt  Rrc  BRI  BRIopt  is a strength and moduli ratio parameter derived from the influence of

OPMC Stabiization. Substituting for q u in Equation (4.20) we obtain,

© 2009 Kensetsu Kaihatsu Limited

  CBR   gl     1    f OPMC   gi  umc      mc     q PI   q (%)    CBR   gl  1     f OPMC    gi  imc    

(4.22)

In evaluating the resulting deterioration in foundation structural capacity as a consequence of moisturesuction variations, relation (4.23) is adopted.

 CBRUS  500 0.9 S r   CBR S0.1 S r 

(4.23)

where ,

Page 43

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

CBRUS CBRs Sr

= = =

Unsoaked CBR Soaked CBR Saturation Level Expressed as fraction of 100 percent

4.4 Consolidation and Settlement Related Analysis 4.4.1 Estimation of Consolidation and Shear Stress Paths As repeated loading progresses, the cumulative effects can be back analyzed by applying the concepts of consolidation and shear stress ratio functions under normally consolidated (NC) conditions introduced by Mukabi and Tatsuoka (1996) and Mukabi (2001d). In so doing, the initial stresses are computed from the experimental results of full scale trial sections (Mukabi, 2002; Gono et al., 2003) .The cumulative stresses are then derived by considering the average loading rate and cumulative repeated loading over a given period of time. Once the maximum deviator and mean effective stresses are determined, the stress ratio functions, defined from the following expressions proposed by Mukabi and Tatsuoka (1999b) and Mukabi (2001d) are applied.

   A  CSR  B
Where,

(4.24)

A and B are material properties, and the consolidation stress ratio function  CSR ,
independent of the effects of loading rate, is derived from the relation

which is



1
~

CSR

qmax , whereby  ' =

function of normalized angle of internal friction expressed as  '   A / IQ (A: An isotropic I: Isotropic) and qm ax = maximum deviator stress.  ' can be determined from the quasi-emprical equation (Mukabi, 2001d) expressed in general form as:

 '   SR  SR /  SR
where,

(4.25)

ASR and BSR are stress ratio constants and  SR  q p ' is the invariant stress ratio variable. The antistrophic stress path is derived from the isotropic one by introducing a mathematical operator proposed by Mukabi and Tatsuoka (1999b) expressed as:

© 2009 Kensetsu Kaihatsu Limited

 

K I     CSR .CSR

m ax I

(4.26)

where,

m ax = (q/p’) at qmax, KI=1 and CSR= consolidations stress ratio. The modifier is applied in the relation
q   p .
On the other hand, the invariant stresses and angle of internal friction under over consolidated (OC) conditions were derived from the flowing correlations proposed by Mukabi (2001d).

Page 44

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

oc qmax 

KoNC

NC KoNC .qmax oc  Ko . A .CSR NC

(4.27)

where,
OC OC K Ox  KOx  OCR
sin  'f

and,
OC KOx  1  sin  ' f

The corresponding mean effective stress, p'fOC and angle of internal friction  'fOC are given by:
NC   PC'OC  Pf' NC KO q 'fOC   NC  OC NC  ' pCNC  K O  K O . A CSR   

(4.28)

and,



'OC f

NC ' NC   KO   NC  f OC NC   KO  KO . A CSR   

1

(4.29)

4.4.2 Analyzing Construction History for Settlement Prediction Computation of total and initial settlement resulting from construction and surcharge of upper layers is considered vital since this influences the characteristics of the foundation soils and the magnitude of their engineering parameters. In computing the total settlement, the generalized Equation (4.30) below was adopted. Computation of total and initial settlement resulting from construction and surcharge of upper layers is considered vital since this influences the characteristics of the soils adjacent to the foundation structure and the magnitude of their engineering parameters. In computing the total settlement, the generalized Equation (4.30) below is adopted.
ij ST  H i i CC 1  ei

i 1, j 1

 log

10 

 P ij  P K iC  o ij P 0 

   

(4.30)

© 2009 Kensetsu Kaihatsu Limited

where, Hi = Thickness of each layer in cm. Back Calculation of induced stresses and strains due to these effects are derived from Equations (4.31) and (4.32) as follows.

C ci 

e i log 10 P0  P  / P0 
k Psc (10i  1)

(4.31)

P0ij 

(4.32)

Where,

Page 45

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

i i   ei Cc i 1
It is assumed that the stress is induced uniformly and that the magnitude of induced stress reduces proportionally with depth. However, the quantitative reduction is average over the depth of each layer as a logarithmic function of the summed reduction in voids ratio (e) and compression Index (CC).

4.5 Shearing Strength and Critical State Analysis 4.5.1 Analysis of a Soil Element along the Slip Failure Plane Concepts developed based on recent research for the derivation of stress ratio functions related to consolidation and undrained shear are adopted in comprehensively analyzing and evaluating the failure modes and critical state conditions for design purposes. The stress invariants and angle of shearing resistance are determined from the following relations.

 SR  0.0422  '0.0455
where,

(4.33)

 SR  q m ax p f  i.e. invariant stress ratio at failure and  ' , which is fundamentally defined as  ' =
Sin-1

 a ' r '  a ' r ' under

triaxial conditions is the Angle of Internal Friction of the

geomaterial. The relation between  ' and (qu)max adopted in this analysis is expressed in Equation (4.34) as:

'

ANf (qu ) max  Af Bf

(4.34)

where, (qu)max values are expressed in kN/m2 and ANf = 0.08 Af = 106, Bf = 3.83 are experimentally determined constants. On the other hand, considering that qmax = ( ' a  ' r ) m ax and P ' f  1 3  ' a 2 ' r  then,

 '  Sin 1 



 q max   2 p' f  1 3q max   

(4.35)

© 2009 Kensetsu Kaihatsu Limited

From Equations (4.33), (4.34) and (4.35) the mean effective stress at failure Pf' is derived as :

 1 1 p 'f  0.5 qmax     Sin ' 3 
or,

(4.36)

 1 1 p' f  0.5 qmax     Sin ANf qU max  A f / B f ' 3   



 

(4.37)

Page 46

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

A more universal empirical equation that considers all factors including the effects of OPMC stabilization, variation in material properties, modes of mechanical and chemical stabilization, as a quantum of various parameters is presented in Equation (4.32) below.
2 q u   gl ln CBR   gi (kgf/cm )

(4.38)

4.5.2 Application of Modified Critical State Soil Mechanics The development of the conventional Critical State Soil Mechanics(CSSM) concepts and theories was predominantly based on the Rendulics principle of effective stress which states that for a soil in an initial state of stress and stress history, there exists a unique relationship between it’s void ratio (e), and effective stress ′ (∆�������� , �������� ∆����′ ). Within this context it is pressumed that for a given, normally consolidated clay, failure occurs at a unique line known as the Critical State Line (CSL) defined by ���� = ��������′, without allowing the stress paths to locate above it at any one stage irrespective of drain conditions, strain rate and the stress path traversed towards the CSL. However, modern research has shown that this unique state does not exist for most of the natural clayey geomaterials for various reasons. Various Researchers for example, have reported that, the shapes and magnitudes of yield envelopes are influenced mainly by the composition, anisotropy and stress history of the clayey features. Based on long term research, Mukabi and Tatsuoka (1992, 1995 and 1999) proposed some modification of certain aspects of the existing theory of CSSM. By determining the ratio of deviation of the Anisotropic stress path (������������)���� , as a function of the Isotropic (������������)���� , they introduced a linear operator Ψ ′ expressed as:
���� Ψ ′ = (����max ⁡ �������� − )/ Δ���� ′ ���� ������������

× ������������

(4.39)

Where,
���� ������������������������������������������������ ������������������������������������, (����max ⁡ = 0.582, �������� = 1, ) Δ���� ′ ���� ������������

= 0.16, ������������ ������������ = �������� /����

Since ���� = ���������������� , the equation ���� = ��������′ defining the conventional ������������ can therefore be defined in the modified form as: ���� = Ψ ′ ����′ (4.40)

On the other hand, the modified ���� constant which would project the modified ������������ onto the ����: ������������′ space is determined from the kappa function ���� = ���� ′ /������������ and the following relation.

© 2009 Kensetsu Kaihatsu Limited

�������� (�������� )���� = ���������������� �������� /���� + ����������������

(4.41)

where, �������� = ���������������� ��������������������������������, (�������� )���� = ���������������� �������������������������������� ���������������������������������������� ������������������������ ������������������������������������������������ ������������������������������������ ����������������������������������������������������, ���������������� = 1.78, �������� /���� ������������ ������������ ���������������� = 0.9

=

The modified Normal Consolidation and Critical State Lines in the ����: ������������′ space may therefore be defined as: ���� = ���� − �������� ������������′ and, (4.42)

Page 47

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

���� = Γ − �������� ������������′

(4.43)

The extrapolation of the consolidation constants to calculate the values of the stresses at failure under undrained or partially drained conditions may therefore be given by Equations (4.43) and (4.44).
′ �������� = ������������ (Γ − �������� )/��������

(4.44)

And,
′ �������� = Ψ ′ ������������ (Γ − �������� )/��������

(4.45)

Another important aspect of this development is that as the bearing ground progresses towards Critical State ′ Conditions tending to failure, the shearing stress path deviates from constant �������� conditions at a virtually constant ratio. Incorporating this concept, an empirically determined deviator stress factor, ���� ′ was proposed as indicated in Equation (4.46). ���� ′ = �������� /{�������� = �������� × �������� × �������� /���� } where, �������� �������� ������������ �������������������������������� ������������������������������������ ������������������������ �������������������������������� ������������������������������������ �������� (���� ′ /����′ ) ≤ 3 (4.46)

4.6 Deformation Resistance Analyses 4.6.1 Application of Deformation Concepts The deterioration with time of the structural capacity of a civil engineering structure has been known to be greatly influenced by the bearing capacity and resistance to deformation of the native soils. For purposes of comprehensively studying this condition in the laboratory by varying a number of parameters, dynamic loading was applied directly on the specimens in order to simulate critical conditions whereby the upper layers of pavement structure would have deteriorated drastically leading to a gross loss of its structural capacity. It was derived analytically that the effect of the damaging factor eff would reduce proportionally D by a factor 
0 .7 SC

 

with the increase in structural capacity of the upper layers. This relation is expressed in

Equation (4.46).

0. eff   SC7 xeff DR DI

(4.47)

© 2009 Kensetsu Kaihatsu Limited

where,
0. eff =Coefficient of Resulting Damaging Effect,  SC7 =Structural Capacity Factor, eff =Coefficient of DR DI

Initial Damaging Effect.

4.6.2 Determination of Modulus of Deformation Parameters Analysis of the elastic Young’s modulus and shear modulus to be adopted in characterizing the deformation behavior of geomaterials are derived from the following Equations.

Page 48

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

For 2 < qn < 15kgf/cm2,
ij E m ax 

E50 n x q (kgf / cm 2 ) (0.0996 qu  0.0104 )

(4.48)

where,

 2  qu q R  0.806
and

n  2.24 e 0.112 qu  1.663

Since

2  qu  15 kgf / cm 2

For 15< qn < 35,

ij C Emax  139x dg x10m xe0.0782qu (kgf / cm2 )

(4.49)

where,
C  dg  1.89qu 0.42  1.45

and

m  qu qR 
For qn > 35 then

0.5

 0.755

ij E m ax 

E50 n x q (kgf / cm 2 ) (0.0996 qu  0.0104 )

For OPMC stabilized aggregate, cementetious material and relatively hard rock, the following equation is adopted. For purposes of evaluating the influence and magnitude of change in voids ratio (e) on the maximum shear modulus of geomaterials, the following Equation is adopted.
∀ ���������������� = ������������ × �������� (������������)

(4.50)

Where, ������������ = 3,379 ������������ ∀= 0.38 ������������ ���������������������������� ���������������������������� ���������������������������� ������������������������������������

© 2009 Kensetsu Kaihatsu Limited

' Go  2360 (2.17  e) 2 (1  e)( o ) 0.6

(4.51)

4.6.3 Computation of Linear Elastic Range In analyzing the effects of dynamic loading, the linear elastic range is a vital parameter since it determines the initial yield surface beyond which the behavior tends towards non-linearity and non-recoverability of elasticity. In other words, the visco-elastic and plastic straining mechanisms leading to failure, prevail. This concept is also quite important in controlling the mode and magnitude of loading during stage construction.

Page 49

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Estimation of the linear elastic range or initial yield surface is made from the following Equation proposed by Mukabi (1998).

 a ij ELS



 a ij 50 ij ij  ELS  a max  A

(%)

(4.52)

Where,

 ESL is a function of the level of ( a ) m ax and A is a constant depending on the physical properties of
the geomaterial. For most clays  is defined as,  ELS  

 E50   x 462 E max  

The analytical results based on this Equation can be adopted in predicting the magnitude of future settlement as a result of dynamic loading as well as the corresponding possible deterioration in the structural capacity of the foundation structure.

4.7 Geophysical Survey Analysis

The equipment adopted in this Study was a portable geo-electromagnetic sounding instrument based on the time domain electromagnetic sounding technology. The modified system is based on the Transient Electromagnetic Method (TEM) sounding technology which enable the conducting of subsurface sounding to as deep as 300m depending mainly on the geological formation, ground conditions, environmental factors and frequency mode. Theoretically, an asymptotic estimation of signals for late stages of transcience are considered. The development of the electromagnetic signal with time, ���� ���� , for a late stage of the transcience ����0 = ���� (����0 ���� 2 /����) ≫ 1, for a transmitting coil with a radius ���� and a receiving coil with a radius ����, lying above the homogeneous half-space with formation resistivity ����, magnetic permeability of vacuum ����0 and current ����, is described by the formula proposed by Kamenetsky, 1997, expressed as follows:

© 2009 Kensetsu Kaihatsu Limited

���� ���� ����

2 = ������������ ���� 2 ����0 /����2 {���� 2 ���� 2 }���� −5/2

1

5

3

(4.52)

The signal for ���� (����0 ���� 2 /����) ≫ 1 does not depend on the radius of the receiving coil (���� < ����). Formula (4.45) is also valid for a height above the surface of the half-space determined by the coil. At a late stage of transcience, the signal registered in the receiving antenna is caused by the currents induced in the ring inside the section with the effective radius ���������������� and the depth ���������������� ~ ���������������� = [��������/����0 )]1/2, exceeding the radius of the transmitting coil, ���������������� ≫ ����.

Page 50

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

The vertical magnetic field created by the coil is homogeneous within the limits of its area at ���� < ���������������� , hence registered signals which are proportional to the derivative of the magnetic field over time do not depend on the station of reception. At an early stage of transient (����0 ≪ 1 and the identical coils (���� = ����), the signals do not depend on the resistivity of the media or ground, hence:

���� ���� ���� = ����0 ����/2����

(4.53)

However, for a small receiving antenna (���� ���� ≪ 1), the signal is proportional to the resistivity of the meadia or ground, but does not depend on time. Consequently, this relation is expressed as:

���� ���� ���� = 3��������(���� 2 ���� 3 )

(4.54)

4.8 Concepts Applied for OPMC Stabilization 4.8.1 Theoretical Considerations

In their natural state, most geomaterials are usually deficient in one or more of the particle fractions required. Consequently, mechanical stabilization plays an important role in achieving a pavement structure which, under loading conditions, is appreciably resistant to shear and deformation. In developing the Optimum Batching Ratio Method (OBRM), Mukabi (2001a) considered that; such geomaterials would have a particle size distribution that tends towards correctly proportioned ratio that would yield optimum density and adequate strength to resist stress-induced deformation. This concept is demonstrated in Figures 4.8.1~4.8.3.

© 2009 Kensetsu Kaihatsu Limited

Figure 4.8.1 – Effect of gradation index on Mechanical Stability

Page 51

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Figure 4.8.2 – Effect of gradation index on Bearing capacity

Figure 4.8.3 – Correlation between mechanical stability, MS and bearing capacity, BC

The theoretical point of departure in establishing this method is that soil is regarded as an assembly of particles whose integrated motion can be characterized theoretically by basic concepts and fundamental principles of continuum mechanics and models that consider probabilistic perspectives of microscopic state and multi-dimensional analysis.

© 2009 Kensetsu Kaihatsu Limited

A summary of the theoretical and empirical basis for this method is presented in Figure 4.8.4 (a) ~ (h), in the form in which the paper was presented at the 14th World Road Congress (IRF 2001) in Paris.

Page 52

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

(a)

(b)
Important factor study

(c)
Objective of

(d)

Develop a method of determining optimum Mixing ratios for geomaterials with different grading characteristics in order to achieve;     Enhanced strength (Bearing Capacity) Better characteristics Compaction

Greater resistance to wear Enhanced properties resilience

(e)

(f)

(h)

(g)

Figure 4.8.4 (a) - (h) Method of Enhancing Mechanical Stabilization of Geomaterials

4.8.2 Proposed Method of Determining Optimum Batching Ratio (OBR) The mechanical stabilization method, developed on the basis of the foregoing theory, is represented graphically in Figures 4.8.5 and 4.8.6 as well as Flow chart 4.1

© 2009 Kensetsu Kaihatsu Limited

Figure 4.8.5 Schematic representation of Grading curves generating Graphical Lines Depicted in Fig. 4.8.6

Page 53

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Fig. 4.8.6 Graphical Representation of New Batching Ratio Method

Flow Chart 4.1 Proposed Batching Ratio Method
Determine Grading for both materials Join the percentages passing for similar sieve sizes for both materials as shown in Fig. 4.3 Plot and join the lower and upper bound of the specification values as shown in Fig. 4.3

Assuming 50:50 Batching Ratio Line as the Phase transformation point, draw Translation Lines from the points where the sieve lines intersect the 50:50 BR Line to the specification Lines (Fig. 4.3)

Mark out the points of intersection at the intersection between the Sieve and Specification Lines (Fig. 4.3)

Calculate individual average Batching Ratios of material from points indicated on Fig. 4.3

Compute overall average Batching Ratio

Calculate the percentages of the respective sieve size for the optimum grading curve

© 2009 Kensetsu Kaihatsu Limited

Plot values in grading envelop

Page 54

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

CHAPTER 5 5. MATERIALS CHARACTERIZATION AND ANALYSIS OF TEST RESULTS 5.1 Basic Physical and Mechanical Parameters Table 5.1.1 and the corresponding graph show the typical grading charachteristics of the Songwe Airport Pozzolanic soils sampled at varying depths and locations along some designated Airport Runway.
SIEVE ANALYSIS According to ASTM;D422 - 63 Sampling Location: Stockpile at km. 2+200 LHS. Sampling Date: 3rd August 2009 Testing Date: Soils Table 5.1.1 Typical Grading Characteristics of Songwe Airport Pozzolanic15th August 2009 Source of Material: Excavated from CUT Section. Initial Dry Mass of Sample Sieve size (mm) m1= Description of Sample: Subbase Material (Neat). g Corrected m 75 50 37.5 28 20 Passing 20 mm Total (checked with m1) Riffled Riffled and Washed Correction Factor 14 10 6.3 5.0 3.35 2.0 1.18 0.600 0.425 0.300 0.212 0.150 0.075 Passing 75 μm Total (checked with m4) Grading Modulus GM 1.5 mF m3 m4 m2/m3 3840 2530 2.055 125.0 170.0 300.0 190.0 280.0 295.0 325.0 200.0 70.0 115.0 180.0 110.0 145.0 25.0 256.9 349.4 616.5 390.5 575.4 606.2 667.9 411.0 143.9 236.3 369.9 226.1 298.0 3.2 4.3 7.6 4.8 7.1 7.5 8.3 5.1 1.8 2.9 4.6 2.8 3.7 94.7 90.4 82.7 77.9 70.8 63.2 55.0 49.9 48.1 45.1 40.6 37.8 34.1 m2 100 70 7890 0 100 70 0.0 1.2 0.9 100 100.0 98.8 97.9 8065 Actual Testing Condition: Washed/ Unwashed Percentage Retained (m/m1)x100 Cumulative % Passing Specification Limits

Mass Retained (g)

100 90 80 70 60 50 40 30 20 10 0
0.01

Particle Size Distribution Chart

% Passing

0.1 Sieve Size (mm) 1

10

© 2009 Kensetsu Kaihatsu Limited

On the other hand, Table 5.1.2 typical pre-treatment (pre-stabilization)/pre-consolidation basic physical, mechanical and bearing capacity properties of soils within the vicinity of the Airport Project Area. Table 5.1.2 Typical Pre-treatment/Pre-consolidation Material Test results for Songwe Airport
B. SUBBASE MATERIAL TEST RESULTS (STOCKPILE AT KM. 2+200 LHS - APPROX. 25,000 CUM) #
1 2 3 4 5 6 7

TESTED PARAMETERS
CBR @ 100% MDD MDD- Kg per Cubic OMC Atterberg - LL Atterberg - PL Atterberg - PI Atterberg - LS

TEST VALUE

SPECIFICATION REQMTS
Subbase

REMARKS
Qualifies

55.00% Not > 35% 1888% Not specified 8.80% Not specified 22.70% Not > 25% 18.10% Not specified 4.60% Not > 6% 2.00% Not specified

Qualifies

Qualifies

Page 55

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

5.2 Correlation between Physical, Mechanical and strength Parameters The typical pre-treatment (pre-stabilization)/pre-consolidation basic physical, mechanical and bearing capacity CONSTRUCTION OF PAVEMENTS AND BUILDINGS AT SONGWE AIRPORT- MBEYA. for material tested from the existing subbase stockpile at km 2+200LHS are summarized in Tables 5.2.1 ~ 5.2.5. Date: 3rd August 2009. The high bearing capacity and strength values con be clearly noted. SUMMARY OF STABILIZATION TEST RESULTS.
MATERIAL SOURCE: S/Base Stockpile at km: 2+200 LHS

Table 5.2.1 Summary of Stabilization Test Results of Songwe Airport km2+200LHS Subbase Stockpile A TEST RESULTS ON NEAT MATERIAL A. Neat Material
TESTED PARAMETERS MDD # OMC LL PL PI LS

kg/m 3 1780

% 14.5

% 24

% 17.6

% 6.4

% 2.8

CBR AT 100% MDD
58

1

B

TEST RESULTS ON STABILIZED MATERIAL (LIME & CEMENT)
Stabilization Agent
Pozzolana # Lime MDD OMC LL TESTED PARAMETERS PL PI LS

B. Cement and Lime Stabilized Material
kg/m 3 1 2 2 3 3 4 4 6 6 1780 1780 1780 1780 1780 1780 1780 1780 1780 1780

% 1

%

% 14.5 14.5 14.5 14.5 14.5 14.5 14.5 14.5 14.5 14.5

% 25.3 25.6 22.3 23.4 23.4 24.3 44 41.7 45 44.4

% 19.1 19.3 17.1 18 18.4 19.3 40 37 41.9 40.7

% 6.2 6.3 5.2 5.4 5 5 4 4.7 3.1 3.7

% 2.8 2.8 2.2 2 2.1 2 2.1 2.5 1.9 2

CBR AT 100% MDD
150 145 190 180 300 180 314 200 360 305

1 2 3 4 5 6 7 8 9 10

Table 5.2.2 Summary of Lime-Stabilized Songwe Airport km2+200LHS Subbase Material Test Results Summary of Stabilization Test Results for Subbase Stockpile Material at km2+200LHS
B Test Results on Stabilized Material (Lime) Stabilization MDD 3 (kg/m ) 1780 1780 1780 1780 OMC (%) 14.5 14.5 14.5 14.5 3/Aug/2009 Tested Parameters PL (%) 19.3 19.3 37.0 40.7 PI (%) 6.3 5.0 4.7 3.7 LS (%) 2.8 2.0 2.5 2.0 CBR Corrected @100%CBR (%) MDD (%) 145 180 200 305 206 292 320 495

Construction of Pavements and Buildings at Songwe Airport, Mbeya - Tanzania

No. Pozzolana (%) 2 4 6 8

Lime (%)

LL (%)

1 3 4 6

25.6 24.3 41.7 44.4

© 2009 Kensetsu Kaihatsu Limited

Construction of Pavements and Buildings at Songwe Airport, Mbeya - Tanzania Table Stabilization Test Cement-Stabilized Stockpile Material at km2+200LHS Summary of5.2.3 Summary ofResults for Subbase km2+200LHS Subbase Material Test Results B Test Results on Stabilized Material (Cement) 3/Aug/2009 Stabilization Tested Parameters No. Pozzolana (%) 2 4 6 8 1 3 4 6 Lime (%) MDD 3 (kg/m ) 1780 1780 1780 1780 OMC (%) 14.5 14.5 14.5 14.5 LL (%) 25.3 23.4 44.0 45.0 PL (%) 19.1 18.4 40.0 41.9 PI (%) 6.2 5.0 4.0 3.1 LS (%) 2.8 2.1 2.1 1.9 CBR Corrected @100%CBR (%) MDD (%) 150 300 314 360 214 486 509 586

Page 56

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 5.2.4 Summary of UCS for Songwe Airport Stabilized Subbase Material added 1%, 2% & 3% PPC

Table 5.2.5 Summary of UCS for Sonwe Airport Stabilized Subbase Material added 1%, 2% & 3% PPC
Before Stabilization
Organic Content

GRADING 37.5 20 10 5 2 425 μm 75 dmax GM μm mm mm mm mm mm mm

ATTERBERG LIMITS

PROCTOR LS % MDD OMC 3

INITIAL CONSUMP. OF LIME (ICL)

© 2009 Kensetsu Kaihatsu Limited

LL % 24

PL % 18

PI % 6

%

Actual

100 97.9 90.4 77.9 63.2 48.1 34.1 CEMENT CONTENT % 1% 2% 3%
ATTERBERG LIMITS

Spec.
After Stabilization

UCS LS % 5 5
4

MATERIAL CLASS

LL % 22 22 22

PL % 17 17
18

PI %

(Mpa) 2.5 2 2 3.59 6.02 7.75

Spec.

Actual

Page 57

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

5.3 Dynamic Cone Penetration Test Results The ground and geomaterial characteristics under dynamic loading as simulated by the Dynamic Cone Penetration determined in this Study, are summarized in theTables below, while their behavior is graphically characterized in the corresponding Figures. The fact that the existing pavement is very sound can be derived from the very high bearaing capacity and strength magnitudes that it exhibits. Series 5.3.1 Tables and Figures for Dynamic Cone Penetration Results for Songwe Airport Ch2+000~ Ch2+400 SONGWE AIRPORT - RUNWAY PROJECT
DCP TEST RESULTS PENETRATION DATA REPORT Chainage(km): Location: Lane no. Offset(m): Surface Type: Cone angle Zero error: Test date: Remarks: 2+000 Lane 2 CENTRELINE Unpaved 60o 60 22/08/2009
WEATHER STATUS Temp: Humidity: Rainfall: Precipitation Period Wind Status

CBR S/ No.

## ## ## ## ## ## ##

1 2 3 4 5 6 7

Initial No. of Cumulative Reading blows Blows (Hi) 0 0 2 2 5 7 5 12 5 17 10 27 10 37 10 47

Final Reading (Hf)

Cumulative Level Penetration Penetration (Hi-Hf) Depth (mm) Depth (mm) 215 215 0 266 266 266.00 275 275 275.00 295 295 295.00 305 305 305.00 322 322 322.00 334 334 334.00 343 343 343.00

Penetration Rate (mm/blow) P 0.00 25.50 1.80 4.00 2.00 1.70 1.20 0.90

CBR (%) 11.92 168.89 76.00 152.00 178.82 253.33 337.78

UCS, qu 2 (kgf/cm ) 2.88 40.78 18.35 36.70 43.18 61.17 81.56

N-Value

5.88 83.33 37.50 75.00 88.24 125.00 166.67

Average CBR for Subbase Course =

168.392

© 2009 Kensetsu Kaihatsu Limited

Page 58

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

SONGWE AIRPORT - RUNWAY DCP TEST RESULTS PENETRATION DATA REPORT Chainage(km): Location: Lane no. Offset(m): Surface Type: Cone angle Zero error: Test date: Remarks: 2.000 Lane 3 Right Hand Side (RHS) Unpaved 60o 60 22/08/2009
WEATHER STATUS Temp: Humidity: Rainfall: Precipitation Period Wind Status

CBR S/ No.

## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ##

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Initial No. of Cumulative Reading blows Blows (Hi) 0 0 5 5 5 10 5 15 5 20 5 25 5 30 5 35 5 40 5 45 5 50 5 55 10 65 10 75 10 85 10 95 10 105 10 115

Final Reading (Hf)

Cumulative Level Penetration Penetration (Hi-Hf) Depth (mm) Depth (mm) 200 200 0 221 221 221 233 233 233 247 247 247 260 260 260 269 269 269 280 280 280 295 295 295 309 309 309 318 318 318 327 327 327 340 340 340 362 362 362 379 379 379 393 393 393 403 403 403 414 414 414 420 420 420

Penetration Rate (mm/blow) P 0.00 4.20 2.40 2.80 2.60 1.80 2.20 3.00 2.80 1.80 1.80 2.60 2.20 1.70 1.40 1.00 1.10 0.60

CBR (%) 72.38 126.67 108.57 116.92 168.89 138.18 101.33 108.57 168.89 168.89 116.92 138.18 178.82 217.14 304.00 276.36 506.67

UCS, qu (kgf/cm2) 17.48 30.58 26.21 28.23 40.78 33.36 24.47 26.21 40.78 40.78 28.23 33.36 43.18 52.43 73.40 66.73 122.33

N-Value

35.71 62.50 53.57 57.69 83.33 68.18 50.00 53.57 83.33 83.33 57.69 68.18 88.24 107.14 150.00 136.36 250.00

Average CBR for Subbase Course =

177.49

© 2009 Kensetsu Kaihatsu Limited

Page 59

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009
SINGWE AIRPORT - RUNWAY DCP TEST RESULTS PENETRATION DATA REPORT Chainage(km): Location: Lane no. Offset(m): Surface Type: Cone angle Zero error: Test date: Remarks: 2.100 Lane 1 Right Hand Side (RHS) Unpaved 60o 60 22/08/2009
WEATHER STATUS Temp: Humidity: Rainfall: Precipitation Period Wind Status

CBR S/ No.

## ## ## ## ## ## ## ## ## ## ## ## ## ## ##

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Initial No. of Cumulative Reading blows Blows (Hi) 0 0 5 5 5 10 5 15 5 20 5 25 5 30 5 35 5 40 5 45 5 50 5 55 10 65 10 75 10 85 10 95

Final Reading (Hf)

Cumulative Level Penetration Penetration (Hi-Hf) Depth (mm) Depth (mm) 210 210 0 243 243 243 265 265 265 285 285 285 294 294 294 312 312 312 325 325 325 339 339 339 354 354 354 360 360 360 380 380 380 390 390 390 418 418 418 438 438 438 460 460 460 472 472 472

Penetration Rate (mm/blow) P 0.00 6.60 4.40 4.00 1.80 3.60 2.60 2.80 3.00 1.20 4.00 2.00 2.80 2.00 2.20 1.20

CBR (%) 46.06 69.09 76.00 168.89 84.44 116.92 108.57 101.33 253.33 76.00 152.00 108.57 152.00 138.18 253.33

UCS, qu (kgf/cm2) 11.12 16.68 18.35 40.78 20.39 28.23 26.21 24.47 61.17 18.35 36.70 26.21 36.70 33.36 61.17

Cumulative N-Value Penetration Depth (mm) 0 22.73 243 34.09 265 37.50 285 83.33 294 41.67 312 57.69 325 53.57 339 50.00 354 125.00 360 37.50 380 75.00 390 53.57 418 75.00 438 68.18 460 125.00 472

© 2009 Kensetsu Kaihatsu Limited

Page 60

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009
SINGWE AIRPORT - RUNWAY DCP TEST RESULTS PENETRATION DATA REPORT Chainage(km): Location: Lane no. Offset(m): Surface Type: Cone angle Zero error: Test date: Remarks: 2.100 11.50m 1 Left Hand Side (LHS) Unpaved 60o 60 22/08/2009
WEATHER STATUS Temp: Humidity: Rainfall: Precipitation Period Wind Status

CBR S/ No. 1 2 3 4 5 6 7 8 9

## ## ## ## ## ## ## ##

Initial No. of Cumulative Reading blows Blows (Hi) 0 0 2 2 2 4 3 7 3 10 5 15 5 20 5 25 5 30

Final Reading (Hf)

Cumulative Level Penetration Penetration (Hi-Hf) Depth (mm) Depth (mm) 200 200 0 222 222 222 244 244 244 263 263 263 275 275 275 305 305 305 325 325 325 344 344 344 353 353 353

Penetration Rate (mm/blow) P 0.00 11.00 11.00 6.33 4.00 6.00 4.00 3.80 1.80

CBR (%) 27.64 27.64 48.03 76.00 50.67 76.00 80.00 168.89

Cumulative UCS, qu N-Value Penetration 2 (kgf/cm ) Depth (mm) 0 6.67 13.64 222 6.67 13.64 244 11.60 23.70 262.99 18.35 37.50 275 12.23 25.00 305 18.35 37.50 325 19.32 39.47 344 40.78 83.33 353

Average CBR for Subbase Course =

69.36

© 2009 Kensetsu Kaihatsu Limited

Page 61

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009
SINGWE AIRPORT - RUNWAY DRY DCP TEST RESULTS PENETRATION DATA REPORT Chainage(km): Location: Lane no. Offset(m): Surface Type: Cone angle Zero error: Test date: Remarks: CBR S/ No. 1 2 3 4 5 6 7 8 9 10 11 2.200 3 Right Hand Side (RHS) Unpaved 60 60 22/08/2009 Final Reading (Hf) Cumulative Level Penetration Penetration (Hi-Hf) Depth (mm) Depth (mm) 195 195 0 213 213 213 219 219 219 226 226 226 233 233 233 240 240 240 253 253 253 257 257 257 270 270 270 277 277 277 280 280 280
o

WEATHER STATUS Temp: Humidity: Rainfall: Precipitation Period Wind Status

## ## ## ## ## ## ## ## ## ##

Initial No. of Cumulative Reading blows Blows (Hi) 0 0 5 5 5 10 5 15 5 20 5 25 10 35 10 45 10 55 10 65 10 75

Penetration Cumulative UCS, qu CBR (%) N-Value Penetration Rate (kgf/cm2) (mm/blow) P Depth (mm) 0.00 0 84.44 20.39 41.67 3.60 213 253.33 61.17 125.00 1.20 219 217.14 52.43 107.14 1.40 226 217.14 52.43 107.14 1.40 233 217.14 52.43 107.14 1.40 240 233.85 56.46 115.38 1.30 253 760.00 183.50 375.00 0.40 257 233.85 56.46 115.38 1.30 270 434.29 104.86 214.29 0.70 277 1013.33 244.67 500.00 0.30 280

Average CBR for Subbase Course =

366.45

© 2009 Kensetsu Kaihatsu Limited

Page 62

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009
SINGWE AIRPORT - RUNWAY DCP TEST RESULTS PENETRATION DATA REPORT Chainage(km): Location: Lane no. Offset(m): Surface Type: Cone angle Zero error: Test date: Remarks: CBR S/ No. 1 2 3 4 5 6 7 8 9 10 11 2.200 3 Left Hand Side (LHS) Unpaved 60o 60 22/08/2009 Final Reading (Hf) Cumulative Level Penetration Penetration (Hi-Hf) Depth (mm) Depth (mm) 199 199 0 218 218 218 235 235 235 245 245 245 259 259 259 270 270 270 280 280 280 287 287 287 290 290 290 300 300 300 303 303 303
WEATHER STATUS Temp: Humidity: Rainfall: Precipitation Period Wind Status

## ## ## ## ## ## ## ## ## ##

Initial No. of Cumulative Reading blows Blows (Hi) 0 0 2 2 2 4 2 6 2 8 2 10 2 12 3 15 5 20 10 30 10 40

Penetration Cumulative UCS, qu CBR (%) N-Value Penetration Rate 2 (kgf/cm ) (mm/blow) P Depth (mm) 0.00 0 32.00 7.73 15.79 9.50 218 35.76 8.64 17.65 8.50 235 60.80 14.68 30.00 5.00 245 43.43 10.49 21.43 7.00 259 55.27 13.35 27.27 5.50 270 60.80 14.68 30.00 5.00 280 130.47 31.50 64.38 2.33 286.99 506.67 122.33 250.00 0.60 290 304.00 73.40 150.00 1.00 300 1013.33 244.67 500.00 0.30 303

Average CBR for Subbase Course =

203.87

© 2009 Kensetsu Kaihatsu Limited

Page 63

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009
SINGWE AIRPORT - RUNWAY DCP TEST RESULTS - DRY PENETRATION DATA REPORT Chainage(km): Location: Lane no. Offset(m): Surface Type: Cone angle Zero error: Test date: Remarks: CBR S/ No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 2.300 11.50m 1 Left Hand Side (LHS) Unpaved 60o 60 22/08/2009 Initial Reading (Hi) Final Reading (Hf) Cumulative Level Penetration Penetration (Hi-Hf) Depth (mm) Depth (mm) 200 200 0 235 235 235 270 270 270 289 289 289 350 350 350 376 376 376 405 405 405 425 425 425 445 445 445 456 456 456 470 470 470 475 475 475 488 488 488 500 500 500 510 510 510 522 522 522 530 530 530 543 543 543 557 557 557 566 566 566 572 572 572 584 584 584 593 593 593 605 605 605 625 625 625 644 644 644 Penetration Rate (mm/blow) P 0.00 17.50 17.50 9.50 30.50 13.00 14.50 10.00 10.00 5.50 7.00 2.50 2.60 2.40 2.00 2.40 1.60 2.60 2.80 1.80 1.20 2.40 1.80 2.40 2.00 1.90
WEATHER STATUS Temp: Humidity: Rainfall: Precipitation Period Wind Status

No. of Cumulative blows Blows 0 2 2 2 2 2 2 2 2 2 2 2 5 5 5 5 5 5 5 5 5 5 5 5 10 10 0 2 4 6 8 10 12 14 16 18 20 22 27 32 37 42 47 52 57 62 67 72 77 82 92 102

CBR (%)

UCS, qu (kgf/cm2) 4.19 4.19 7.73 2.41 5.65 5.06 7.34 7.34 13.35 10.49 29.36 28.23 30.58 36.70 30.58 45.88 28.23 26.21 40.78 61.17 30.58 40.78 30.58 36.70 38.63

## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ##

17.37 17.37 32.00 9.97 23.38 20.97 30.40 30.40 55.27 43.43 121.60 116.92 126.67 152.00 126.67 190.00 116.92 108.57 168.89 253.33 126.67 168.89 126.67 152.00 160.00

Cumulative N-Value Penetration Depth (mm) 0 8.57 235 8.57 270 15.79 289 4.92 350 11.54 376 10.34 405 15.00 425 15.00 445 27.27 456 21.43 470 60.00 475 57.69 488 62.50 500 75.00 510 62.50 522 93.75 530 57.69 543 53.57 557 83.33 566 125.00 572 62.50 584 83.33 593 62.50 605 75.00 625 78.95 644

Average CBR for Subbase Course =

99.85

© 2009 Kensetsu Kaihatsu Limited

Page 64

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

SONGWE AIRPORT - RUNWAY DCP TEST RESULTS DRY PENETRATION DATA REPORT Chainage(km): Location: Lane no. Offset(m): Surface Type: Cone angle Zero error: Test date: Remarks: CBR S/ No. 1 2 3 4 5 6 7 8 9 10 2.300 11.50m 3 Right Hand Side (RHS) Unpaved 60o 60 22/08/2009 Final Reading (Hf) Cumulative Level Penetration Penetration (Hi-Hf) Depth (mm) Depth (mm) 206 206 0 219 219 219 227 227 227 234 234 234 236 236 236 245 245 245 247 247 247 251 251 251 260 260 260 265 265 265
WEATHER STATUS Temp: Humidity: Rainfall: Precipitation Period Wind Status

## ## ## ## ## ## ## ## ##

Initial No. of Cumulative Reading blows Blows (Hi) 0 0 5 5 5 10 5 15 5 20 5 25 5 30 10 40 10 50 10 60

Penetration Cumulative UCS, qu CBR (%) N-Value Penetration Rate 2 (kgf/cm ) (mm/blow) P Depth (mm) 0.00 0 116.92 28.23 57.69 2.60 219 190.00 45.88 93.75 1.60 227 217.14 52.43 107.14 1.40 234 760.00 183.50 375.00 0.40 236 168.89 40.78 83.33 1.80 245 760.00 183.50 375.00 0.40 247 760.00 183.50 375.00 0.40 251 337.78 81.56 166.67 0.90 260 608.00 146.80 300.00 0.50 265

Average CBR for Subbase Course =

435.41

© 2009 Kensetsu Kaihatsu Limited

Page 65

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009
SINGWE AIRPORT - RUNWAY DCP TEST RESULTS PENETRATION DATA REPORT Chainage(km): Location: Lane no. Offset(m): Surface Type: Cone angle Zero error: Test date: Remarks: CBR S/ No. 1 2 3 4 5 6 7 2.400 11.50m 1 Left Hand Side (LHS) Unpaved 60 60 22/08/2009 Final Reading (Hf) Cumulative Level Penetration Penetration (Hi-Hf) Depth (mm) Depth (mm) 195 195 0 214 214 214 220 220 220 223 223 223 228 228 228 237 237 237 243 243 243
o

WEATHER STATUS Temp: Humidity: Rainfall: Precipitation Period Wind Status

## ## ## ## ## ##

Initial No. of Cumulative Reading blows Blows (Hi) 0 0 5 5 5 10 5 15 10 25 10 35 10 45

Penetration Cumulative UCS, qu CBR (%) N-Value Penetration Rate 2 (kgf/cm ) (mm/blow) P Depth (mm) 0.00 0 80.00 19.32 39.47 3.80 214 253.33 61.17 125.00 1.20 220 506.67 122.33 250.00 0.60 223 608.00 146.80 300.00 0.50 228 337.78 81.56 166.67 0.90 237 506.67 122.33 250.00 0.60 243

Average CBR for Subbase Course =

254.72

© 2009 Kensetsu Kaihatsu Limited

Page 66

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009
SINGWE AIRPORT - RUNWAY DCP TEST RESULTS PENETRATION DATA REPORT Chainage(km): Location: Lane no. Offset(m): Surface Type: Cone angle Zero error: Test date: Remarks: CBR S/ No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 2.400 11.50m 3 Right Hand Side (RHS) Unpaved 60 60 22/08/2009 Final Reading (Hf) Cumulative Level Penetration Penetration (Hi-Hf) Depth (mm) Depth (mm) 203 203 0 220 220 220 240 240 240 260 260 260 276 276 276 294 294 294 305 305 305 320 320 320 327 327 327 340 340 340 350 350 350 363 363 363 390 390 390 415 415 415 440 440 440 460 460 460 482 482 482 508 508 508 510 510 510
o

WEATHER STATUS Temp: Humidity: Rainfall: Precipitation Period Wind Status

## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ##

Initial No. of Cumulative Reading blows Blows (Hi) 0 0 5 5 5 10 5 15 5 20 5 25 5 30 5 35 5 40 5 45 5 50 5 55 10 65 10 75 10 85 10 95 10 105 10 115 10 125

Penetration UCS, qu CBR (%) Rate (kgf/cm2) (mm/blow) P 0.00 89.41 21.59 3.40 76.00 18.35 4.00 76.00 18.35 4.00 95.00 22.94 3.20 84.44 20.39 3.60 138.18 33.36 2.20 101.33 24.47 3.00 217.14 52.43 1.40 116.92 28.23 2.60 152.00 36.70 2.00 116.92 28.23 2.60 112.59 27.19 2.70 121.60 29.36 2.50 121.60 29.36 2.50 152.00 36.70 2.00 138.18 33.36 2.20 116.92 28.23 2.60 1520.00 367.00 0.20

Cumulative N-Value Penetration Depth (mm) 0 44.12 220 37.50 240 37.50 260 46.88 276 41.67 294 68.18 305 50.00 320 107.14 327 57.69 340 75.00 350 57.69 363 55.56 390 60.00 415 60.00 440 75.00 460 68.18 482 57.69 508 750.00 510

Average CBR for Subbase Course =

394.03

© 2009 Kensetsu Kaihatsu Limited

Page 67

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

The following derivations can further be made from these tables and figures. a. Most of the locations on the carriageway of the existing pavement structure exhibit high bearing strengths under conditions tested with averages of CBR > 348. b. Most locations exhibit high CBR values right from the depth of testing. This is a clear indication that the overlaying material is also superior similar to the underlaying material which has hitherto undergone long-term consolidation under dynamic loading. c. It is vital to determine the appropriate section CBR for design purposes. This is undertaken in Chapter 7.

The mean CBR values are shown in the following Tables 5.3.2. Table 5.3.2 CBR Data and CBRM Values from Dynamic Cone Penetration Results for Songwe Airport Runway Ch2+000 to Ch2+400
KM 2+000 - CL Penetration Thickness, t CBR (%) Depth (mm) (mm) 215 266 275 295 305 322 334 343 1000 266 9 20 10 17 12 9 657 0.00 11.92 168.89 76.00 152.00 178.82 253.33 337.78 337.78 CBR
P

KM 2+000 - RHS t x CBR
P

KM 2+100 - RHS CBR
P

KM 2+100 -LHS CBR
P

Penetration Thickness, t CBR (%) Depth (mm) (mm) 200 221 233 247 260 269 280 295 309 318 327 340 362 379 393 403 414 420 1000 221 12 14 13 9 11 15 14 9 9 13 22 17 14 10 11 6 580 0.00 72.38 126.67 108.57 116.92 168.89 138.18 101.33 108.57 168.89 168.89 116.92 138.18 178.82 217.14 304.00 276.36 506.67 506.67

t x CBR

P

Penetration Thickness, t CBR (%) Depth (mm) (mm) 210 243 265 285 294 312 325 339 354 360 380 390 418 438 460 472 1000 243 22 20 9 18 13 14 15 6 20 10 28 20 22 12 528 0.00 46.06 69.09 76.00 168.89 84.44 116.92 108.57 101.33 253.33 76.00 152.00 108.57 152.00 138.18 253.33 253.33

t x CBR

P

Penetration Thickness, t CBR (%) Depth (mm) (mm) 200 222 244 263 275 305 325 344 353 1000 222 22 19 12 30 20 19 9 647 0.00 27.64 27.64 48.03 76.00 50.67 76.00 80.00 168.89 168.89

CBRP 0.00 3.02 3.02 3.63 4.24 3.70 4.24 4.31 5.53 5.53

t x CBRP 0 671.19 66.51 69.06 50.83 111.01 84.72 81.87 49.75 3576.33

0.00 2.28 5.53 4.24 5.34 5.63 6.33 6.96 6.96

0 607.66 49.75 84.72 53.37 95.78 75.93 62.68 4575.54

Sum CBRM

5605.42 216.63

0.00 4.17 5.02 4.77 4.89 5.53 5.17 4.66 4.77 5.53 5.53 4.89 5.17 5.63 6.01 6.72 6.51 7.97 7.97 Sum CBRM

0 921.02 60.27 66.79 63.57 49.75 56.87 69.93 66.79 49.75 49.75 63.57 113.74 95.78 84.15 67.24 71.65 47.83 4623.83 6622.26 357.21

0.00 3.58 4.10 4.24 5.53 4.39 4.89 4.77 4.66 6.33 4.24 5.34 4.77 5.34 5.17 6.33 6.33

0 871.06 90.27 84.72 49.75 78.97 63.57 66.79 69.93 37.96 84.72 53.37 133.58 106.74 113.74 75.93 3340.91

Sum CBRM

5322.00 185.41

Sum CBRM

4761.28 132.76

KM 2+200 -RHS Penetration Thickness, t CBR (%) CBRP Depth (mm) (mm) 195 213 219 226 233 240 253 257 270 277 280 1000 213 6 7 7 7 13 4 13 7 3 720 0.00 84.44 253.33 217.14 217.14 217.14 233.85 760.00 233.85 434.29 1013.33 1013.33 0.00 4.39 6.33 6.01 6.01 6.01 6.16 9.13 6.16 7.57 10.04 10.04

t x CBRP 0 934.48 37.96 42.07 42.07 42.07 80.09 36.50 80.09 53.01 30.13 7231.86

KM 2+200 -LHS Penetration Thickness, t CBR (%) CBRP Depth (mm) (mm) 199 218 235 245 259 270 280 287 290 300 303 1000 218 17 10 14 11 10 7 3 10 3 697 0.00 32.00 35.76 60.80 43.43 55.27 60.80 130.47 506.67 304.00 1013.33 1013.33 0.00 3.17 3.29 3.93 3.51 3.81 3.93 5.07 7.97 6.72 10.04 10.04

t x CBRP 0 692.11 56.01 39.32 49.21 41.90 39.32 35.50 23.92 67.24 30.13 7000.84

KM 2+300 -LHS Penetration Thickness, t CBR (%) CBRP Depth (mm) (mm) 200 235 270 289 350 376 405 425 445 456 470 475 488 500 510 522 530 543 557 566 572 584 593 605 625 644 1000 235 35 19 61 26 29 20 20 11 14 5 13 12 10 12 8 13 14 9 6 12 9 12 20 19 356 0.00 17.37 17.37 32.00 9.97 23.38 20.97 30.40 30.40 55.27 43.43 121.60 116.92 126.67 152.00 126.67 190.00 116.92 108.57 168.89 253.33 126.67 168.89 126.67 152.00 160.00 160.00 0.00 2.59 2.59 3.17 2.15 2.86 2.76 3.12 3.12 3.81 3.51 4.95 4.89 5.02 5.34 5.02 5.75 4.89 4.77 5.53 6.33 5.02 5.53 5.02 5.34 5.43 5.43 Sum CBRM

t x CBRP 0 608.62 90.65 60.32 131.28 74.35 79.96 62.42 62.42 41.90 49.21 24.77 63.57 60.27 53.37 60.27 45.99 63.57 66.79 49.75 37.96 60.27 49.75 60.27 106.74 103.15 1932.67 4100.26 84.79

KM 2+300 -RHS Penetration Thickness, t CBR (%) CBRP Depth (mm) (mm) 206 219 227 234 236 245 247 251 260 265 1000 219 8 7 2 9 2 4 9 5 735 0.00 116.92 190.00 217.14 760.00 168.89 760.00 760.00 337.78 608.00 608.00 0.00 4.89 5.75 6.01 9.13 5.53 9.13 9.13 6.96 8.47 8.47

t x CBRP 0 1070.89 45.99 42.07 18.25 49.75 18.25 36.50 62.68 42.36 6226.66

© 2009 Kensetsu Kaihatsu Limited

Sum CBRM

8610.35 785.18

Sum CBRM

8075.51 647.76

Sum CBRM

7613.41 542.80

Page 68

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

KM 2+400 -LHS Penetration Thickness, t CBR (%) Depth (mm) (mm) 195 214 220 223 228 237 243 1000 195 19 6 3 5 9 6 757 0.00 80.00 253.33 506.67 608.00 337.78 506.67 506.67 CBRP 0.00 4.31 6.33 7.97 8.47 6.96 7.97 7.97 t x CBRP 0.00 81.87 37.96 23.92 42.36 62.68 47.83 6034.90

KM 2+400 -RHS Penetration Thickness, t CBR (%) Depth (mm) (mm) 203 220 240 260 276 294 305 320 327 340 350 363 390 415 440 460 482 508 510 1000 203 17 20 20 16 18 11 15 7 13 10 13 27 25 25 20 22 26 2 490 0.00 89.41 76.00 76.00 95.00 84.44 138.18 101.33 217.14 116.92 152.00 116.92 112.59 121.60 121.60 152.00 138.18 116.92 1520.00 1520.00 CBRP 0.00 4.47 4.24 4.24 4.56 4.39 5.17 4.66 6.01 4.89 5.34 4.89 4.83 4.95 4.95 5.34 5.17 4.89 11.50 11.50 t x CBRP 0.00 76.02 84.72 84.72 73.01 78.97 56.87 69.93 42.07 63.57 53.37 63.57 130.38 123.86 123.86 106.74 113.74 127.14 23.00 5633.92

Sum CBRM

6331.52 312.20

Sum CBRM

7129.42 445.73

© 2009 Kensetsu Kaihatsu Limited

Page 69

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

5.4 AggregateTest Results The typical sieve analysis results of the coarse aggregate are presented in Table 5.4.1 and the corresponding figure, while those of the fine aggregate are shown if Tables 5.4.2 and 5.4.3. Table 5.4.4 and the corresponding figure are a summary of the typical characteristics if the coarse aggregates. It can be noted that all the material tested indicates appreciable mechanical stability. Table 5.4.1 Lab Sieve Analysis Results of Coarse Aggregate for Songwe Airport - Runway

© 2009 Kensetsu Kaihatsu Limited

Page 70

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 5.4.2 Lab Sieve Analysis Results of FineAggregate for Songwe Airport - Runway

© 2009 Kensetsu Kaihatsu Limited

Page 71

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 5.4.3 Fineness Modulus of Fine Aggregate for Songwe Airport - Runway

© 2009 Kensetsu Kaihatsu Limited

Page 72

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 5.4.4 Lab Sieve Analysis Results of CRS for Songwe Airport - Runway

© 2009 Kensetsu Kaihatsu Limited

Table 5.4.5 is a summary of the strength and quality test results of the aggregates from Idiga, Magereza 1, Magereza 2 and Mlowo-Mbozi stone quarries. The results show that all the stone quarries tested are of high quality with very high strengths, which is characteristic of the geomaterial within that region.

Page 73

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 5.4.5 Summary of Stone Quarries Materials Tests Results for Songwe Airport in Mbeya
1. IDIGA QUARRY SPECIFICATION REQMTS #
1 2 3 4 5

TESTED PARAMETERS
Aggregate Crushing Value (ACV) Los Angeles Abrasion test (LAA) Ten Percent Fines (TFV) Soundness of Aggreg. By Sodium Sulphate Soln Specific Gravity & Water Absorption- Coarse Aggreg.

TEST VALUE

Crushed Aggreg Base Asphalt Concrete Coarse. Surface Coarse Not > 30% Not > 30% Not < 100% Not > 9% Not > 3%

Asphalt Treated Base Course Not > 35% Not > 40% Not < 75% Not > 12% Not > 3%

REMARKS
Qualifies Qualifies Qualifies Qualifies Qualifies

10.20% Not > 30% 16% Not > 45% 411KN Not < 100% 0.40% Not > 12% 0.27% Not > 3%

2. MAGEREZA QUARRY 1 SPECIFICATION REQMTS #
1 2 3 4 5

TESTED PARAMETERS
Aggregate Crushing Value (ACV) Los Angeles Abrasion test (LAA) Ten Percent Fines (TFV) Soundness of Aggreg. By Sodium Sulphate Soln Specific Gravity & Water Absorption- Coarse Aggreg.

TEST VALUE

Crushed Aggreg Base Asphalt Concrete Coarse. Surface Coarse Not > 30% Not > 30% Not < 100% Not > 9% Not > 3%

Asphalt Treated Base Course Not > 35% Not > 40% Not < 75% Not > 12% Not > 3%

REMARKS
Qualifies Qualifies Qualifies Qualifies Qualifies

10.20% Not > 30% 22% Not > 45% 249KN Not < 100% 0.40% Not > 12% 1.31% Not > 3%

3. MAGEREZA QUARRY 2 SPECIFICATION REQMTS #
1 2 3 4 5

TESTED PARAMETERS
Aggregate Crushing Value (ACV) Los Angeles Abrasion test (LAA) Ten Percent Fines (TFV) Soundness of Aggreg. By Sodium Sulphate Soln Specific Gravity & Water Absorption- Coarse Aggreg.

TEST VALUE

Crushed Aggreg Base Asphalt Concrete Coarse. Surface Coarse Not > 30% Not > 30% Not < 100% Not > 9% Not > 3%

Asphalt Treated Base Course Not > 35% Not > 40% Not < 75% Not > 12% Not > 3%

REMARKS
Qualifies Qualifies Qualifies Qualifies Qualifies

10.20% Not > 30% 18% Not > 45% 275KN Not < 100% 0.40% Not > 12% 0.82% Not > 3%

3. MLOWO-MBOZI QUARRY SPECIFICATION REQMTS #
1 2 3 4 5

TESTED PARAMETERS
Aggregate Crushing Value (ACV) Los Angeles Abrasion test (LAA) Ten Percent Fines (TFV) Soundness of Aggreg. By Sodium Sulphate Soln Specific Gravity & Water Absorption- Coarse Aggreg.

TEST VALUE

Crushed Aggreg Base Asphalt Concrete Coarse. Surface Coarse Not > 30% Not > 30% Not < 100% Not > 9% Not > 3%

Asphalt Treated Base Course Not > 35% Not > 40% Not < 75% Not > 12% Not > 3%

REMARKS
Qualifies Qualifies Qualifies Qualifies Qualifies

10.20% Not > 30% 33% Not > 45% 142KN Not < 100% 0.40% Not > 12% 0.91% Not > 3%

5.5 Summary of Bearing Capacity and Shearing Strength Parameters A summary of the bearing capacity and shear strength parameters determined from in-situ tests is given in Table 5.5.1~ 5.5.3, whilst the graphical characteristics of the CBR Mean against the chainage tested are depicted in Fig. 5.5.1. Table 5.5.2 show the results of the lime stabilized material, while Fig. 5.5.3 shows the same for the cement stabilized materials. In both cases the effect of chemical stabilization (treatment) can be appreciated. This may be appreciated to the pozzolanic nature of the existing geomaterial.

© 2009 Kensetsu Kaihatsu Limited

Page 74

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 5.5.1-1 Summary of Bearing Capacity and Shearing Strength Parameters for Songwe Airport UCS qu M r cor CBRM (%) Emax / qmax Serial No. Location N-Value (MPa) (MPa) 1 2+000-CL 217 5.23 106.89 8383 3178 2 2+000-RHS 357 8.63 176.25 5762 9145 3 2+100-RHS 185 4.48 91.48 9505 2569 4 2+100-LHS 133 3.21 65.50 12591 1832 5 2+200-RHS 785 18.96 387.41 3560 103537 6 2+200-LHS 648 15.64 319.60 3950 55555 7 2+300-LHS 85 2.05 41.84 18741 1289 8 2+300-RHS 543 13.11 267.82 4381 31584 9 2+400-LHS 312 7.54 154.04 6344 6497 10 2+400-RHS 446 10.76 219.92 4960 17189

Fig. 5.5.1 CBR Mean values at Chainages on Songwe Airport Runway

© 2009 Kensetsu Kaihatsu Limited

Table 5.5.1-2 Dry and Wet CBR (Mean), UCS and N-Value Computations
CBRM (%) Serial No. Location Original Wet Dry MC Corrected Vales Original UCS qu (MPa) Wet Dry MC Corrected Vales Original Wet N-Value Dry MC Corrected Vales

1 2 3 4 5 6 7 8 9 10

2+000 2+000 2+100 2+100 2+200 2+200 2+300 2+300 2+400 2+400

CL RHS RHS LHS RHS LHS RHS LHS RHS LHS

217 357 185 133 785 648 85 543 312 446

5.23 8.63 4.48 3.21 18.96 15.64 2.05 13.11 7.54 10.76

106.89 176.25 91.48 65.50 387.41 319.60 41.84 267.82 154.04 219.92

Page 75

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 5.5.2 Summary of Lime-Stabilized Subbase Material Tests Results for Songwe Airport Project

B

Test Results on Stabilized Material (Lime) CBR @100%CBR (%) LTC MDD (%) UCS, qu (MPa) UCS, qu (MPa) [LTC]

3/Aug/2009 N-Value (LTC) 101.64 144.07 157.89 244.23

Lime (%)

N-Value 71.54 88.81 98.68 150.49

1 145 206 3.50 4.97 3 180 292 4.35 7.05 4 200 320 4.83 7.73 6 305 495 7.37 11.95 LTC: Computed Values considering Long Term Consolidation effects

Table 5.5.3 Summary of Cement-Stabilized Subbase Material Tests Results for Songwe Airport Project B Test Results on Stabilized Material (Cement) 3/Aug/2009
CBR @100%UCS, qu LTC CBR (%) UCS, qu (MPa) MDD (%) (MPa) [LTC] N-Value (LTC) 105.59 239.79 251.14 289.13

Cement (%)

N-Value 74.01 148.02 154.93 177.62

1 150 214 3.62 5.17 3 300 486 7.25 11.74 4 314 509 7.58 12.29 6 360 586 8.69 14.15 LTC: Computed Values considering Long Term Consolidation effects

5.6 Bearing Capacity Test Results The Bearing Capacity test results are presented in the preceding sections 5.3 and 5.5 of this Report. 5.7 Consolidation Test Results The importance of studying consolidation properties was considered for three main reasons: 1. 2. To analyze the effect of chemical stabilization on consolidation properties since consolidation is one of the methods commonly applied for ground improvement. To evaluate whether or not and to what extent water infiltration or groundwater seepage would affect the consolidation properties of the chemically stabilized geomaterials associated with settlement and reduction in magnitude of shear stress as well as resistance to deformation. To evaluate whether further secondary consolidation is likely to occur to a detrimental extent that would cause settlement particularly for the lower layers under surcharge and dynamic traffic loading.

© 2009 Kensetsu Kaihatsu Limited

3.

In general, the following observations can be made from Tables 5.7.1 and 5.7.2. (a) (b) (c) (d) Chemical stabilization enhances the vital consolidation parameters such as CSR, CSR and . The degree of influence of the chemical stabilization on the vital consolidation parameters depends on the type of geomaterial The curing period has minimal effect on the magnitude of the vital consolidation parameters The correlation of the vital consolidation parameters is quite consistent notwithstanding the curing or soaking conditions

Page 76

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 5.7.1(a) Summary of Consolidation Stress Parameters Derived from Laboratory Tests
Serial No. Location UCS qu (MPa)

 CSR
53.412 59.954 60.564 62.571 56.202 68.067 69.069 72.429

CSR 1.326 1.365 1.368 1.379 1.343 1.407 1.412 1.428


16.658 17.723 17.823 18.150 17.113 19.044 19.208 19.754

 /  CSR
0.312 0.296 0.294 0.290 0.304 0.280 0.278 0.273

 1 
0.992 0.975 0.974 0.970 0.985 0.960 0.958 0.953

SR C



KO
0.383 0.339 0.335 0.322 0.364 0.288 0.282 0.263

1 ac K C (MPa)

1  rc

qC (MPa) 5.80 11.59 12.13 13.91 8.27 18.78 19.67 22.64 1.28 2.29 2.38 2.64 1.74 3.25 3.35 3.65

pC’ (MPa) 7.93 15.41 16.09 18.30 11.17 24.19 25.25 28.72

(MPa)

1 2 3 4 5 6 7 8

3.62 7.25 7.58 8.69 5.17 11.74 12.29 14.15

1.048 1.183 1.196 1.238 1.105 1.354 1.375 1.447

0.364 0.345 0.343 0.338 0.355 0.325 0.322 0.315

7.08 13.89 14.51 16.55 10.01 22.03 23.01 26.29

2+000 - LHS

Table 5.7.1(b) Summary of Consolidation Stress Parameters Derived from Laboratory Tests
Serial No. Location UCS qu (MPa)

UCS, qu LTC

UCS, qu

 CSR
54.039 57.741 60.866 53.407 57.199 59.963

CSR 1.330 1.352 1.370 1.326 1.349 1.365


16.760 17.363 17.872 16.658 17.275 17.725

 /  CSR
0.310 0.301 0.294 0.312 0.302 0.296

 1 
0.991 0.981 0.973 0.992 0.982 0.975

SR C



KO
0.379 0.353 0.333 0.383 0.357 0.339

1 ac K C (MPa)

1  rc

qC (MPa) 6.35 9.63 12.40 5.79 9.15 11.60

pC’ (MPa) 8.67 12.93 16.43 7.92 12.31 15.42

(MPa)

1
2+000 - 2+400

Measured

3.97 6.02 7.75 3.62 5.72 7.25

1.060 1.137 1.202 1.047 1.126 1.183

0.362 0.351 0.343 0.364 0.353 0.345

7.74 11.61 14.82 7.07 11.05 13.89

1.39 1.98 2.42 1.28 1.90 2.29

2 3 4 5 6

Table 5.7.2 Summary of Consolidation Stress Parameters Derived from In-situ Tests
Serial No. Location UCS qu (MPa)

Computed

 CSR
56.317 62.449 54.956 52.659 81.117 75.123 50.567 70.544 60.486 66.310

CSR 1.344 1.378 1.336 1.321 1.465 1.440 1.308 1.419 1.367 1.398

   /  CSR  1  
17.131 18.130 16.910 16.536 21.169 20.193 16.195 19.448 17.810 18.758 0.304 0.290 0.308 0.314 0.261 0.269 0.320 0.276 0.294 0.283 0.984 0.970 0.988 0.995 0.942 0.949 1.001 0.956 0.974 0.963

SR C

KO
0.363 0.323 0.372 0.389 0.218 0.249 0.404 0.274 0.335 0.299

1 1 K C  ac  rc (MPa) (MPa)

qC

pC’

1 2 3 4 5 6 7 8 9 10

2+000 2+000 2+100 2+100 2+200 2+200 2+300 2+300 2+400 2+400

CL RHS RHS LHS RHS LHS RHS LHS RHS LHS

5.23 8.63 4.48 3.21 18.96 15.64 2.05 13.11 7.54 10.76

1.107 1.235 1.079 1.032 1.636 1.505 0.989 1.407 1.194 1.317

0.355 0.339 0.359 0.366 0.297 0.309 0.372 0.319 0.344 0.329

10.13 16.42 8.71 6.28 34.58 28.89 4.04 24.46 14.43 20.29

1.76 2.62 1.54 1.15 4.24 3.86 0.76 3.48 2.37 3.07

(MPa) (MPa) 8.37 11.30 13.80 18.17 7.16 9.73 5.13 7.04 30.34 37.41 25.03 31.46 3.28 4.54 20.97 26.78 12.06 16.01 17.22 22.34

© 2009 Kensetsu Kaihatsu Limited

5.8 Shearing Strength Test Results The shearing strength parameters are summarized in Tables 5.8.1 Series present the UCS laboratory test results for specimens tested at 1%, 2% and 3% cement treatment levels, while the graphical chacteristics of the loading to failure are shown in the corresponding figures. Table 5.8.2 is a summary of these results in comparison with values that are computed adopting empirical equations defined in Chapter 4. On the other hand, a summary of the shear parameters derived from in-situ tests is given in Table 5.8.3. This Table presents the results computed by adopting Equations 4.18 in sub-section 4.3.1 and 4.33 ~ 4.38 in sub-section 4.5.1 of Chapter 4. The derivations from these results are briefly presented after Table 5.8.3.

Page 77

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Tables 5.8.1 Series - Summary of Shearing Strength Parameters from Laboratory UCS Tests
1% CEMENT Load Calib. Factor = S/NO. TIME (MIN.) 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0.1795 LOAD (STRESS)-KN 40 80.2 120.3 160.4 200.5 240.6 280.7 320.8 360.9 401 40 80 125 166 205 239 280 315 366 405 28.7 57.4 86.1 114.8 143.5 172.2 200.9 229.6 258.3 287 Area= 0.01824m2 Specimen Dimensions Diameter: 152.40mm Strain, εa (%) DISPLACEMENT / STRAIN (mm) 0.16 0.13 0.31 0.24 0.47 0.37 0.62 0.49 0.78 0.61 0.93 0.73 1.09 0.86 1.24 0.98 1.4 1.10 1.55 1.22 0.11 0.09 0.22 0.17 0.33 0.26 0.44 0.35 0.55 0.43 0.66 0.52 0.78 0.61 0.89 0.70 0.99 0.78 1.12 0.88 0.15 0.12 0.3 0.24 0.45 0.35 0.6 0.47 0.76 0.60 0.89 0.70 1.06 0.83 1.21 0.95 1.35 1.06 1.52 1.20 Height: 127.00mm 2 Factored Stress UCS -KN/m (Kpa) UCS- Mpa 0.718 39.36403509 0.039364035 14.3959 789.2489035 0.789248904 21.59385 1183.873355 1.183873355 28.7918 1578.497807 1.578497807 35.98975 1973.122259 1.973122259 43.1877 2367.746711 2.367746711 50.38565 2762.371162 2.762371162 57.5836 3156.995614 3.156995614 64.78155 3551.620066 3.551620066 71.9795 3946.244518 3.946244518 7.18 393.6403509 0.393640351 14.36 787.2807018 0.787280702 22.4375 1230.126096 1.230126096 29.797 1633.607456 1.633607456 36.7975 2017.406798 2.017406798 42.9005 2352.001096 2.352001096 50.26 2755.482456 2.755482456 56.5425 3099.917763 3.099917763 65.697 3601.809211 3.601809211 72.6975 3985.608553 3.985608553 5.15165 282.4369518 0.282436952 10.3033 564.8739035 0.564873904 15.45495 847.3108553 0.847310855 20.6066 1129.747807 1.129747807 25.75825 1412.184759 1.412184759 30.9099 1694.621711 1.694621711 36.06155 1977.058662 1.977058662 41.2132 2259.495614 2.259495614 46.36485 2541.932566 2.541932566 51.5165 2824.369518 2.824369518

1

2

3

© 2009 Kensetsu Kaihatsu Limited

Page 78

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

2% CEMENT Load Calib. Factor = S/NO. TIME (MINS.) 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 6.5 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 6.5 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 6.5 0.1795 LOAD (STRESS)-KN 38.6 77.1 115.7 154.2 198.2 231.3 269.9 308.4 346.9 385.5 583 45 89.8 134.7 179.6 224.5 269.4 314.3 359.2 404.1 449 625 61.4 122.7 184.1 245.4 306.8 368.1 429.5 490.8 552.2 613.5 627

Area= 0.01824m2 Factored (Load) Stress -KN 6.9287 13.83945 20.76815 27.6789 35.5769 41.51835 48.44705 55.3578 62.26855 69.19725 104.6485 8.0775 16.1191 24.17865 32.2382 40.29775 48.3573 56.41685 64.4764 72.53595 80.5955 112.1875 11.0213 22.02465 33.04595 44.0493 55.0706 66.07395 77.09525 88.0986 99.1199 110.12325 112.5465

Specimen Dimensions Height: 127.00mm UCS -KN/m2(Kpa) UCS- Mpa 379.8629386 0.379862939 758.7417763 0.758741776 1138.604715 1.138604715 1517.483553 1.517483553 1950.487939 1.950487939 2276.225329 2.276225329 2656.088268 2.656088268 3034.967105 3.034967105 3413.845943 3.413845943 3793.708882 3.793708882 5737.308114 5.737308114 442.8453947 0.442845395 883.7225877 0.883722588 1325.583882 1.325583882 1767.445175 1.767445175 2209.306469 2.209306469 2651.167763 2.651167763 3093.029057 3.093029057 3534.890351 3.534890351 3976.751645 3.976751645 4418.612939 4.418612939 6150.630482 6.150630482 604.2379386 0.604237939 1207.491776 1.207491776 1811.729715 1.811729715 2414.983553 2.414983553 3019.221491 3.019221491 3622.475329 3.622475329 4226.713268 4.226713268 4829.967105 4.829967105 5434.205044 5.434205044 6037.458882 6.037458882 6170.3125 6.1703125 Diameter: 152.40mm Strain, εa (%) DISPLACEMENT / STRAIN (mm) 0.34 0.27 0.67 0.53 1.01 0.80 1.34 1.06 1.68 1.32 2.01 1.58 2.35 1.85 2.68 2.11 3.02 2.38 3.35 2.64 4.43 3.49 0.22 0.17 0.43 0.34 0.65 0.51 0.86 0.68 1.08 0.85 1.29 1.02 1.51 1.19 1.72 1.35 1.94 1.53 2.2 1.73 3.3 2.60 0.21 0.17 0.44 0.35 0.64 0.50 0.87 0.69 1.07 0.84 1.3 1.02 1.52 1.20 1.73 1.36 1.93 1.52 2.14 1.69 2.14 1.69

1

2

3

© 2009 Kensetsu Kaihatsu Limited

Page 79

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

3% CEMENT Load Calib. Factor = S/NO. TIME (Mins.) 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 6 0.1795 LOAD (STRESS)-KN 76.5 153 229.5 306 382.5 459 535.5 612 688.5 770 72.4 144.7 217.1 289.4 361.8 434.1 506.5 578.8 651.2 739.2 74 148.8 223.2 297.6 372 446.4 520.8 595.8 669.6 744 853

Area= 0.01824m2 Factored Stress 13.73175 27.4635 41.19525 54.927 68.65875 82.3905 96.12225 109.854 123.58575 138.215 12.9958 25.97365 38.96945 51.9473 64.9431 77.92095 90.91675 103.8946 116.8904 132.6864 13.283 26.7096 40.0644 53.4192 66.774 80.1288 93.4836 106.9461 120.1932 133.548 153.1135

Specimen Dimensions Height: 127.00mm UCS -KN/m2(Kpa) UCS- Mpa 752.8371711 0.752837171 1505.674342 1.505674342 2258.511513 2.258511513 3011.348684 3.011348684 3764.185855 3.764185855 4517.023026 4.517023026 5269.860197 5.269860197 6022.697368 6.022697368 6775.534539 6.775534539 7577.576754 7.577576754 712.4890351 0.712489035 1423.993969 1.423993969 2136.483004 2.136483004 2847.987939 2.847987939 3560.476974 3.560476974 4271.981908 4.271981908 4984.470943 4.984470943 5695.975877 5.695975877 6408.464912 6.408464912 7274.473684 7.274473684 728.2346491 0.728234649 1464.342105 1.464342105 2196.513158 2.196513158 2928.684211 2.928684211 3660.855263 3.660855263 4393.026316 4.393026316 5125.197368 5.125197368 5863.273026 5.863273026 6589.539474 6.589539474 7321.710526 7.321710526 8394.380482 8.394380482 Diameter: 152.40mm S DISPLACEMENT / STRAIN (mm) train, εa (%) 0.45 0.35 0.9 0.71 1.35 1.06 1.8 1.42 2.25 1.77 2.7 2.13 3.15 2.48 3.6 2.83 4.05 3.19 4.5 3.54 0.45 0.35 0.9 0.71 1.35 1.06 1.86 1.46 2.24 1.76 2.68 2.11 3.2 2.52 3.66 2.88 4 3.15 4.55 3.58 0.32 0.25 0.63 0.50 0.95 0.75 1.26 0.99 1.58 1.24 1.59 1.25 2.21 1.74 2.52 1.98 2.84 2.24 3.15 2.48 3.81 3.00

1

2

3

Note:
* Not representative of the mean Crushing Strength Values

The loads at failure represents the actual Failure Load, which are the Max in every set of Bookings.

© 2009 Kensetsu Kaihatsu Limited

Page 80

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 5.8.2 Comparison of Computed and Measured Mean UCS at different Cement Contents
Measured Computed Cement Content 1% 2% 3% Mean UCS (Mpa) 3.97 6.02 7.75 3.62 5.72 7.25 Difference (%) 8.80 4.90 6.50

Table 5.8.3 Summary of Shear Stress Parameters Derived from In-situ Tests
S/N Location UCS qu (MPa) N-Value Cu (MPa)

q max
(MPa)

' f (MPa)

P

ɸ'A Average

' a

' r

 SR
1.2337 1.3059 1.2177 1.1906 1.5257 1.4551 1.1660 1.4012 1.2828 1.3513

(MPa)

(MPa)

1 2 3 4 5 6 7 8 9 10

2+000 2+000 2+100 2+100 2+200 2+200 2+300 2+300 2+400 2+400

CL RHS RHS LHS RHS LHS RHS LHS RHS LHS

5.23 8.63 4.48 3.21 18.96 15.64 2.05 13.11 7.54 10.76

106.89 176.25 91.48 65.50 387.41 319.60 41.84 267.82 154.04 219.92

2.62 4.31 2.24 1.60 9.48 7.82 1.02 6.55 3.77 5.38

8.37 13.80 7.16 5.13 30.34 25.03 3.28 20.97 12.06 17.22

6.90 10.71 5.98 4.39 20.02 17.35 2.86 15.12 9.54 12.90

30.313 32.023 29.933 29.292 37.232 35.559 28.708 34.282 31.476 33.101

10.13 16.42 8.71 6.28 34.58 28.89 4.04 24.46 14.43 20.29

1.76 2.62 1.54 1.15 4.24 3.86 0.76 3.48 2.37 3.07

The following observations can be made from the foregoing Tables 5.8.1 ~ 5.8.3 and the corresponding Figures. 1) The laboratory test results indicate enhanced intrinsic shearing properties of the pozzolanic material even at very low cement treatment ratios (ref. to results of 1% additative to comparative parameters presented in Chapter 7 from various International Agencies). 2) The in-situ test results show that the shearing strength is immensely enhanced as a result of the coupled effects of long term consolidation and cementetious agglogeration. 3) From Table 5.8.2, it can be observed that there is a very good agreement between the tested and computed values. This confirms the precision of the test results accordingly. 4) On te average, the in-situ values are higher that the laboratory test results {UCSlab = 7.75 MPa compared to UCSin-situ = 8.95 MPa(average)}. However, as can be observed from the results summarized in Tables 5.5.2 and 5.5.3 in the preceding section 5.5, the results tend to be very similar when corrected for the effects of Long Term Consolidation by applying the following equation.
LTC qm ax 

K

STC 0

 1n t / t0 A 'CSR STC

STC STC K 0  qm ax



© 2009 Kensetsu Kaihatsu Limited

Where, Superscript LTC and STC denote long term and short term consolidation respectively whereas t : LTC time and to : STC time., for OC conditions (a/t)fcSTC=1. 5.9 Modulus of Deformation, Elastic Modulus and Linear Elastic Range A summary of the derived modulus of deformation, elastic and shear modulus and elastic limit strain, which is defined as the range of linear elastic and recoverable behavior, given in Tables 5.9.1 and 5.9.2, were computed by applying Equations 4.48 ~ 4.52. The normalized relations are also presented in the same Tables.

Page 81

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 5.9.1(a) Summary of Modulus of Deformation Parameters from Lab Test Results
S/N Location UCS qu (MPa) E50 (MPa) Emax (MPa) Gmax (MPa) ΦELS (εa)max (calculated) (%) (εa)50 (calculated) (%) (εa)ELS (10-3) (%) Emax / qmax M r cor (MPa)

1 2 3 4 5 6 7 8

3.62 7.25 7.58 8.69 5.17 11.74 12.29 14.15

90 180 188 216 128 292 305 352

5511 7171 7297 7686 6307 8614 8767 9249

1837 2390 2432 2562 2102 2871 2922 3083

7.55 11.60 11.93 12.99 9.41 15.64 16.10 17.57

1.049 1.723 1.785 1.992 1.336 2.558 2.661 3.007

0.496 0.894 0.932 1.054 0.666 1.388 1.450 1.654

0.8118 1.4356 1.4921 1.6756 1.0817 2.1593 2.2444 2.5222

951 619 601 553 763 459 446 408

20453 59166 65874 93372 31203 223651 258127 402797

2+000 - LHS

Table 5.9.1(b) Summary of Modulus of Deformation Parameters from Laboratory Test Results
S/N Location UCS qu (MPa) E50 (MPa) Emax (MPa) Gmax (MPa) ΦELS (εa)max (calculated) (%) (εa)50 (calculated) (%) (εa)ELS (10-3) (%) Emax / qmax

UCS, qu LTC

UCS, qu

1

Measured

3.97 6.02 7.75 3.62 5.72 7.25

99 150 193 90 142 180

5706 6684 7357 5509 6555 7173

1902 2228 2452 1836 2185 2391

7.99 10.34 12.09 7.54 10.02 11.60

1.113 1.495 1.817 1.048 1.439 1.724

0.534 0.760 0.950 0.496 0.727 0.895

0.8729 1.2282 1.5199 0.8113 1.1768 1.4364

898 694 593 951 716 618

3 4 5 6

2+000 - 2+400

2

Table 5.9.2 Summary of Modulus of Deformation Parameters from In-situ Test Results
Serial No. 1 2 3 4 5 6 7 8 9 10 Location 2+000 2+000 2+100 2+100 2+200 2+200 2+300 2+300 2+400 2+400 CL RHS RHS LHS RHS LHS RHS LHS RHS LHS E50 (MPa) 1300 2144 1113 797 4712 3887 509 3257 1874 2675 Emax (MPa) 6337 7663 5973 5261 10337 9608 4437 8984 7281 8336 Gmax (MPa) 2112.27 2554.39 1990.98 1753.64 3445.59 3202.67 1478.93 2994.60 2426.95 2778.58

The results basically indicate that, for stiff geomaterial such as the one tested, the shearing strength increases virtually directly proportionally to the deformation resistance. 5.10 Deformation Properties and Linear Elastic Range The results of deformation properties and the linear elastic range are presented in Table 5.10.1 below. The results basically indicate that as the shearing strength increases with the deformation resistance, the linear elastic range is immensely enhanced. Table 5.10.1 Summary of Modulus of Deformation Parameters from in-situ Test Results
Serial No. 1 2 3 4 5 6 7 8 9 10 Location 2+000 2+000 2+100 2+100 2+200 2+200 2+300 2+300 2+400 2+400 CL RHS RHS LHS RHS LHS RHS LHS RHS LHS ΦELS 94.78 129.24 86.07 69.97 210.61 186.92 52.99 167.52 118.89 148.26
(εa)max (εa)50 (calculated) (%) (calculated) (%) (εa)ELS (10-3) (%)

© 2009 Kensetsu Kaihatsu Limited

Computed

Emax / qmax 757 555 834 1026 341 384 1354 428 604 484

1.35 1.98 1.21 0.97 3.90 3.28 0.76 2.81 1.78 2.38

0.672878 1.046328 0.589942 0.450077 2.183231 1.818174 0.322645 1.539348 0.926759 1.281482

0.920771 1.218304 0.834484 0.670794 1.532337 1.493999 0.501741 1.432929 1.138095 1.341260

Page 82

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

5.11 Durability Test Results Durability tests were carried out in accordance with the method described in Section 3.5 of Chapter 3 of this Report. The results of the durability tests performed Pozzolanic material are tabulated in Table 5.11.1 and graphically presented in the corresponding figure. The corresponding characteristic curves plotted in this figure depict the relation between the average losses from wet-dry cycles and the number of wet-dry cycles. Table 5.11.1 Durability Characteristics Based on the Average Percentage of Material Loss for 1%, 2%, & 3% Cement-treated Materials
No. of Cycles 1 2 3 4 5 6 7 8 9 10 11 12 Average % Material Loss 1% 0.33 1.53 1.90 1.90 1.03 0.87 0.93 0.57 0.80 0.17 0.00 0.03 2% 0.27 0.60 0.40 0.40 0.17 0.13 0.20 0.23 0.03 0.17 0.03 0.07 Cummulative Ave. % Material Loss 3% 1% Cement 2% Cement 3% Cement 0.17 0.33 0.27 0.17 0.40 1.87 0.87 0.57 0.37 3.77 1.27 0.93 0.23 5.67 1.67 1.17 0.13 6.70 1.83 1.30 0.10 7.57 1.97 1.40 0.10 8.50 2.17 1.50 0.20 9.07 2.40 1.70 0.10 9.87 2.43 1.80 0.13 10.03 2.60 1.93 0.01 10.03 2.63 1.95 0.03 10.07 2.70 1.98

12.00

Cummulative Average Percentage Material Loss

Cumm. Ave. % of Material Loss

10.00 8.00

6.00
4.00 2.00 0.00

1% Cement 2% Cement
3% Cement

0

2

4

6

8

10

12

14

© 2009 Kensetsu Kaihatsu Limited

No. of Cycles

From the above results, it can be derived that: (a) Cement stabilization enhances durability of the geomaterials tested. (b) The degree of enhancement of the cement stabilization is quite consistent with the number of cycles applied. (c) The relationship between the average losses and number of wet-dry cycles is generally hyperbolic tending towards a residual state as the average losses increase.

Page 83

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

CHAPTER 6 6. APPLICATION OF TEST RESULTS 6.1 Basic Physical and Mechanical Parameters For purposes of quantifying the magnitude of change of the physical properties of the existing foundation geomaterials and their corresponding effects on the bearimg capacity, strength, moduli of deformation, basic parameters such as natural moisture content (wn), Atterberg Limits (PI, LL, WL, & LS), Specific Gravity (Gs), voids ratio (e), dry density (d) and degree of saturation (Sr) were determined based on the standard soil model expressions. In soil mechanics, plasticity index is a function of the amount of clay present in a soil, while the Liquid Limit and Plastic Limits individually are functions of both the amount and type of clay. High plasticity indices are analogous to high water contents whose lubricating effect of the water films between adjacent soil particles tends to reduce the mechanical stability, strength and deformation resistance. The results from the Aterberg Limits will be used to mainly study the quantitative effects of moisture~suction variations of the site soils based on Equations (4.1) ~ (4.6) presented in Chapter 4 of this Report.

6.2 Borehole Log Results Borehole results are mainly analyzed from two paramount perspectives, namely Soil Classification and Penetration Resistance.



Soil Classification

These results will mainly be used for purposes of coming up with a soils description that can convey sufficient information to enable the designers and constructors to appreciate the nature and properties of the soils and to anticipate the likely behavior and potential problems. The results have been comprehensively analyzed with an aim to: (1) Provide a systematic soil description for both a hand specimen and a stratum within a soil deposit in order to, as much as possible, clearly define the nature of the soil in existence at the Project Site. (2) Determine values of soil classification parameters from laboratory tests including particle density, grading, bulk density, moisture content and consistency limits. (3) Utilize accordingly, the soil classification results extrapolatively in evaluating the geotechnical engineering soundness of the design and construction of the foundation and any other geostructure within the Project. (4) Apply the soil model to the determination of a range of parameters used in soil mechanics to denote the state or condition of a soil.

© 2009 Kensetsu Kaihatsu Limited



Penetration Resistance

From the results obtained in the field in refence to the penetration resistance during drilling and dynamic cone penetration, Equations (4.14) ~ (4.19) are utilized in determining the bearing capacity, and strength of the geomaterials and foundation ground tested.

Page 84

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

6.3 Dynamic Penetration Test Results Results obtained from the Dynamic Cone Penetration testing have been versatile in utility whereby they yielded various useful geotechnical engineering parameters that can be used for design and construction QC, including bearing capacity, strength and deformation resistance. The DCP test results are utilized as the main parameters in Equations (4.1) ~ (4.44).

6.4 Aggregate Test Results The purpose of undertaking aggregate tests was to confirm their quality and strength accordingly. The test results are applied in analyzing the contribution of the aggregate particles to the mechanical stability, bearing capacity, strength and deformation resistance of the composite pavement structure.

6.5 Laboratory Test Results The utilization of laboratory test results has been discussed in the preceding sub-section 6.1.

6.6

Bearing Capacity Test Results

The bearing capacity results were basically derived from the Dynamic Cone Penetration Tests. In this study, the results are applied as stipulated below. (a) Overall structural analysis of the composite structure (b) Comparison of CBR results determined from this Study to the design criteria designated by various agencies worldwide. (c) Comparison of the CBR results determined from this Study to the specification criteria of this Project for purposes of analyzing the range and/or level of enhancement of the bearing and structural capacity properties.

(d) Evaluation of heavy load performance in relation to the structurural requirements.

6.7 Consolidation Test Results As demonstrated in sub-section 4.4 of this Report, the consolidation test results is are predominantly applied for the prediction of the post-construction secondary consolidation settlement.

© 2009 Kensetsu Kaihatsu Limited

6.8 Shearing Strength Test Results 6.8.1 Application of Principle Stresses within the Soil Elements The principle stresses ’a and ’r are applied in carrying out the analysis of the deflection within the interface of the overlaying and foundation layers in order to mainly determine the following facts.

Page 85

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

(a) (b) (c)

The the magnitude and/or extent of the interface and layer deflection under dynamic loading. Analysis of the point load effect by the traffic tyre pressure of heavy trucks with respect to each foundation pad. Determine the level and extent of the vertical and radial stress distribution particularly within the shear banding of the slip surface for developing effective countermeasures for the stability of the foundation structure Determine shear stresses that would cause and resist failure.

(d)

6.8.2 Shearing Strength Test Results Shearing strength test results were applied in; (a) (b) (c) (d) (e) Determining the strength required to resist the forces and stresses that may act to cause failure. Calculation of the stability of the foundation ground geo-structure Analysis of stability of the OPMC stabilized layers. Determination of bearing capacity factors for the design of the foundation structure on the existing bearing ground. Analysis of the stability of bearing capacity of the foundation ground

6.9 Modulus of Deformation and Elastic Modulus Test Results Application of the modulus of deformation E50 and elastic modulus Emax was made in reference to (a) Deflection analysis as discussed in various preceding sections (b) Prediction of the resulting quasi-elastic (initial) time dependent settlement caused by both static and dynamic loading (c) Prediction of cumulative settlement with increased repetitive loading over designated time periods.

(d) Prediction of post-construction secondary consolidation settlement as comprehensively discussed under various sections.

© 2009 Kensetsu Kaihatsu Limited

6.10 Deformation Properties and Linear Elastic Range The application of results related to deformation properties and linear elastic range is discussed under subsetion 4.6.3.

6.11 Durability Test Results These results are utilized in analysis in order to:  Determine the suitability and extent of stabilization particularly for the subbase and base course materials.  Determine the resilience of the stabilized materials under particularly severe environmental and dynamic loading conditions.

Page 86

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

CHAPTER 7 7. PAVEMENT STRUCTURAL DESIGN 7.1 Scope This chapter reviews the Original (Existing) pavement design, determines the design based on the US FAA/ ICAO method of Design, analyzes various options and recommends the VE based design for the Songwe Airport aimed at serving aircraft with gross weights of upto 334,800kgs (ie. B747-100). The design review is limited to the Airport Pavement and does not include geometric design or design for any other of the airport facilities. 7.2 Fundamental Design Philosophy The design largely adopts the recommendations made through the Advisory Circular (AC) No. 150/5320-6D dated April 30th, 2004, “Airport Pavement Design and Evaluation”. Reference is also made to the 747 Airplane Characteristics – Airport Planning D6-58326 published in May 1984 by Commercial Airplane Company, which is a Division of the Boeing Company. The Design Philosophy is based on the United States Federal Aviation Administration (FAA) and the International Civil Aviation Organisation (ICAO) recommended practices. The basic design considerations made herein include but are not limited to: 1) The flexible pavement design is based on CBR method of design. 2) Gear configurations are considered by adopting theoretical concepts and empirically developed data. 3) Composite structural considerations have been made in reference to the surface course, base course, subbase and subgrade that can support a Boeing 747-100. 4) The design considers proper and adequate provision of hydraulic facilities as well as periodic and preventive maintenance. 5) The design life considered is 20 years from date of completion of the pavement structure. 6) As cited in the Advisory Circular, the pavement structural thickness is determined on the basis of theoretical analysis of load distribution through the pavement and soils, the analysis of experimental pavement data, environmental factors, Case Study Analysis, among other considerations (ref. to tables 7.2.1 – 7.2.3). 7) Reference is also made to Annex 14 to the Convention on International Civil Aviation Volume 1 in general and Section 2.6 of Chapter 2 regarding Strength of pavements, in Particular. Table 7.2.1 Summary of Major Design Considerations
Item 1. 2. 3. Parameter Aircraft Model and Specification Airplane Configuration Landing and Takeoff Weights 3.1 Maximum Landing Weight 3.2 Maximum Takeoff Weight Maximum Structural Payload General Characteristics General Dimensions including Ground Clearances Consideration Wide Body aircraft – B747-100, 100B Ref. to Table 7.2.2 710,000lb (322,000kgs) to 750,000lb (340,000kgs) Takeoff weight (TOW) 265,300kgs 340,100kgs 75,330kgs Ref. to Table 7.2.3 Ref. to Fig. 7.2.1, Fig. 7.2.2

© 2009 Kensetsu Kaihatsu Limited

4. 5. 6.

-

Page 87

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Item 7. 8. 9.

Parameter Landing Gear Type and Geometry (Footprint) Maximum Design Taxi Weight Gear Tyre Pressures 9.1 Weight on Main Landing Gear 9.2 Nose Gear 9.3 Main Gear Maximum Pavement Loads Landing Gear Loading on Pavement Flexible Pavement Requirements adopting FAA Design Method Minimum Non-stabilized BC thickness = 150mm (P.49) Minimum Thickness for Stabilized BC = 103mm (≈100mm) Equivalency Factor of 1.45 is adopted (ref. Table 3-9 of AC))

-

Consideration Double Dual Tandem Gear Ref. to Fig. 7.2.3 334,800kgs 318,060kgs 2 14.5kgf/cm 2 16.3kgf/cm Ref. to Table 7.2.4 Ref. to Fig. 7.2.4 Ref. to Fig. 7.2.5

10. 11. 12.

Table 7.2.2 Technical Specifications for Boeing Aircraft detailing the B747-100
Measurement Cockpit Crew Typical seating capacity Length Wingspan Tail height Weight empty Maximum takeoff weight Cruising speed (at 35,000 ft altitude) Maximum speed Required runway at MTOW* Maximum range at MTOW Max. fuel capacity Engine models (x 4) 747-100 747-200B Three 747-300

Engine thrust (per engine)

© 2009 Kensetsu Kaihatsu Limited

452 (2-class) 496 (2-class) 366 (3-class) 412 (3-class) 231 ft 10 in (70.6 m) 195 ft 8 in (59.6 m) 63 ft 5 in (19.3 m) 358,000 lb 383,000 lb 392,800 lb (162,400 kg) (174,000 kg) (178,100 kg) 735,000 lb 833,000 lb (333,390 kg) (377,842 kg) Mach 0.84 (555 mph, 893 km/h, 481 knots ) Mach 0.89 (594 mph, 955 km/h, 516 kn) 10,466 ft (3,190 m) 10,893 ft (3,320 m) 5,300 nmi 6,850 nmi 6,700 nmi (9,800 km) (12,700 km) (12,400 km) 48,445 U.S. gal 52,410 U.S. gal (40,339 imp gal/183,380 L) (43,640 imp gal/199,158 L) PW JT9D-7A PW JT9D-7R4G2 PW JT9D-7R4G2 RR RB211-524B2 GE CF6-50E2 GE CF6-80C2B1 RR RB211-524D4 RR RB211-524D4 PW 46,500 lbf PW 54,750 lbf PW 54,750 lbf (207 kN) (244 kN) (244 kN) RR 50,100 lbf GE 52,500 lbf GE 55,640 lbf (223 kN) (234 kN) (247 kN) RR 53,000 lbf RR 53,000 lbf (236 kN) (236 kN)

Sources: 747 specifications, 747 airport report, 747-8 airport brochure 2 The 747 parasitic drag, CDP, is 0.022, and the wing area is 5,500 square feet (511 m ), so that f equals about 121 sq ft or 11.2 m². The parasitic drag is given by ½ f ρair v² in which f is the product of drag coefficient CDp and the wing area.

Page 88

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 7.2.3 General characteristics of the Model 747-100 Aircraft

© 2009 Kensetsu Kaihatsu Limited

Fig. 7.2.1 General Dimensions of the Model 747-100 Aircraft

Page 89

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Fig. 7.2.2 Ground Clearances – Passenger Configurations Model 747-100 Aircraft

© 2009 Kensetsu Kaihatsu Limited

Fig. 7.2.3 Landing Gear Footprint for Model 747-100 Aircraft

Page 90

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 7.2.4 Maximum Pavement Loads of the Model 747-100 Aircraft

© 2009 Kensetsu Kaihatsu Limited

Fig. 7.2.4 Landing Gear Loading on Pavement - Model 747-100 Aircraft

Page 91

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

This Study

© 2009 Kensetsu Kaihatsu Limited

Fig. 7.2.5 Flexible Pavement Requirements – U.S. Army Corps of Engineers Design Method S-77-1 and FAA Design Method - Model 747-100 Aircraft 7.3 Comparison of Design Data with Various Design Criteria 7.3.1 Comparison of Design Criteria for Physical, Strength and Bearing Capacity Parameters In Chapter 5 comprehensive and detailed materials characterization and data analysis was carried out. In this section, the data that was determined from the various tests and analysis is compared with the design criteria specified by several International Agencies to establish its suitability as design parameters. Table 7.3.1 presents a comparison of the results determined from The Songwe Airport Design Review Study and design criteria stipulated by various Agencies for critical design parameters such as Plasticity Index PI, Unconfined Compression Strength (UCS) and California Bearing Ratio (CBR) for Pavements under Traffic Dynamic Loading.

Page 92

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 7.3.1 Comparison of Design Criteria - Physical, Strength & Bearing Capacity of Stabilized Materials Pavement Layer Source UCS CBR PI (MPa) (%) (%) Subbase TRL 0.75~1.5 > 70 < 10 Materials ASSHTO JRA 10 < 10 KRDM > 60 < 12 US FAA > 60 ≤6 This Study 2.1~18.9 85~785 5 (Existing Ground) Base Course TRL G: 1.5 ~ 3.0 > 100 <6 Material H:3.0 ~ 6.0 ASSHTO 2.8~5.25 JRA 2.5~3.0 <9 KRDM 1.8 > 160 < 10 US FAA >80 <6 This Study (CTPG) 7.75~11.7 300~486 5 Notes:
a. b. PI : Plasticity Index, UCS : Unconfined Compression Strength, CBR : California Bearing Ratio TRL : Transport Research Laboratory,London, AASHTO : American Association of State Highway Officials, JRA : Japan Road Association, KRDM : Kenya Road Design Manual.USFAA: United States Federation of Aviation Administration. Results from This Study were determined from tests performed on various OPMC Stabilized Materials under 7 days cure + 7 days Soak Conditions Cement additive percentage –Subbase : 4~6%, Base Course : 4~8% : This Study : 1 ~ 3% for Base Course. CTPG : Cement Treated Pozzolanic Geomaterial

c. d. e.

In general, it can be appreciated that the Pozzolanic material that was tested at Songwe Airport yields engineering design parameters that are well above the criteria stipulated by virtually all the Agencies presented herein. 7.3.2 Comparison of Applicable Specification Criteria for Stabilized Natural Gravel and Design Parameters The comparison of applicable specification criteria for stabilized natural gravel and design parameters determined from this study is tabulated in Table 7.3.2. Table 7.3.2 Comparisons of Spec. Criteria -Stabilized Natural Gravel & Design Parameters - This Study Pavement Layer Reference PI _ 12 <15 5 <6 5 PM <1200 492 <240 141~282 _ CBR (%) _ >50 > 30 209~283 > 160 391~611 UCS (MPa) _ >1.24 1.5~3.0 2.1~18.9 3.0~6.0 7.75~11.7

© 2009 Kensetsu Kaihatsu Limited

Subgrade Material Subbase Materials Base Course Material

Spec. This Study Spec. This Study Spec. This Study

It can be derived from Table 7.3.2 that the values determined from the research undertaken in this study are superior in comparison to the Specification Criteria.

Page 93

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

7.3.3 Comparison of Modulus of Deformation Parameters One of the most important parameters for structural design of a pavement structure is the elastic modulus. Table 7.3.3 presents a comparison of ranges of elastic modulus referred from various sources and researchers as well as that determined from this study. Table 7.3.3 Comparisons of Ranges of Elasticity Modulus for Structural Design from Various Sources Pavement Elastic Modulus Values, Emax (MPa) Layer Type This Study Fossbereg Wang Helekelom Mitchell/ (Material) St: 6~8% /Mitchell /Klomp Shen St : 3~6% St : 3~8% St : 7% Subgrade (St : 0%) _ 140 ~ 1200 _ _ 4397 Subbase (St ; 3%) _ _ 350~ 21 00 1400~ 5722 6300 Base Course (St :3%) 7000 ~ _ 10500~ 7357 15000 18900 Lean _ _ _ 15000~ _ Concrete 30000 PCC _ 21000~ _ _ 35000
Notes: 1. St : Percentage of Cement Stabilization excluding the PCC and Lean Concrete 2. Results from This Study were determined from tests performed on Cement Treated Pozzolanic Materials tested subsequent to 7 days cure + 7 days Soak Conditions 3. Cement additive percentage –Subbase : 3%, Base Course : 3% for this Study.

As can be noted from Table 7.3.3 the comparison is made of pavement materials basically stabilized with cement at percentage ranges of 4~8%. However, it is important to recall that the base course material in this study is pozzolanic material treated with only 3% cement. It can be distinctly derived that the elastic modulus results from this study exhibit higher values than those reported by other Researchers or Agencies in spite of the lower percentage of cement. 7.3.4 Comparison of Durability Parameters The results presented in Table 7.3.4 indicate that, in comparison to the criteria stipulated by the American Portland Cement Association, the losses determined from the wet-dry testing cycles to simulate the durability of the improved geomaterials are well within the required specifications. Table 7.3.4 Comparison of design Criteria for Durability Tests Based on Data from American Portland Cement Association (APCA) and This Study

© 2009 Kensetsu Kaihatsu Limited

Pavement Layer Subgrade Subbase Base Course

Losses from Wet-Dry Cycles (%) This Study APCA 14 2.7 10 1.98 7

This primarily implies that application of the pozzolanic cement treated goematerial for the airport pavement will endure any critical environmental and dynamic loading conditions as well as wearing and deformation resistance over a considerable period of time as is required by the US FAA/ICAO.

Page 94

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

7.3.5 Comparison of Tested Material Properties and Secified Requirements Table 7.3.5 presents the test results of Songwe Airport materials in comparison to the Specified Requirements for design and construction of the pavements including runway, taxiway and apron. Table 7.3.5 Comparison of Songwe Airport Material Results to Specified Material Requirements
Material Requirements Specifications and Results
Material Requirement Specifications Songwe Airport Results
14.5 1.787 >50 0.51 1.778 >98 <0.1

Layer of use

© 2009 Kensetsu Kaihatsu Limited

Bitumen

DT/ NDT Testing Parameter OMC (%) MDD (t/m3) CBR@95%MDD (%) Natural Road Field Moisture (%) bed 3 Dry Density (t/m ) (Sub grade) Degree of compaction (%) >90% Swell (%) CBR wet OMC (%) MDD (t/m3) CBR @ 95% MDD (%) Field Moisture (%) Embankment Dry Density (t/m3) Degree of compaction (%) >90% CBR dry CBR wet R Grading • Maximum • % Passing 0.075 • Uniformity Coefficient -Minimum R Plasticity Index Maximum R Plasticity Modulus •Mix in place •Mix in plant Subbase R Soaked CBR Minimum R Organic Matter Maximum R CBR @95% MDD (modified AASHTO) 7 days cure + 7 days soak R PI LL Cement type: OPC KS02-21 No addition Additive % • Plastic Gravels • Clayey Sands R Grading • Maximum • % Passing 0.075 • Uniformity Coefficient -Minimum R Plasticity Index Maximum R Plasticity Modulus •Mix in place •Mix in plant R Socked CBR Minimum Base Course R Organic Matter Maximum R UCS @95% MDD (modified AASHTO) 7 days cure + 7 days soak R PI PM Cement type: OPC KS02-21 No addition Additive % • Plastic Gravels • Clayey Sands CBR@95%MDD (%) Aggregate Crushing Value (ACV) Los Angeles Abrasion (LAA) Ten percent Fines (TFV) Sodium Sulphate Soundness (SSS) Specific Gravity / Water Absorption 3 Density (t/m ) Wearing Course Voids Ratio (%)

Laboratory In-situ

Laboratory

Remarks

>95%

≤3

In-situ

Pre-Treatment

10~15mm 40 30

14.0mm 341 5

Laboratory

≤2500 2% 60 ≤6 <25 2~49 2~3 2~40mm 35 10 6 ≤1500 ≤700 30 0.5% 1.8MPa <6% ≤250 5~8% 5~7% >80 ≤30 ≤40 >100 <12 <3

240 55
300 4.6 22.7 Not tested Not tested

Not measured

QUALITY CONTROL / CHECKING

Post-Treatment

Pre-Treatment

11.0 34 5 240 240 310 Not measured 7.75MPa 4 96 300 10 16~33 142~411 0.40 0.27~1.31

Laboratory

Post-Treatment

Computed

Laboratory

% % kN % %

Aggregates

In-situ

Stability (kN) Flow (mm) Degree of compaction (%) >90% Thickness (mm) Road bed Embankment Subbase (PL) Subbase (EG) Base Course (OD) (CRS) Base Course (OPMC) (Cement Stabilized) DBST Binder Course (AC) Asphalt Concrete (AC) Wearing Course Shoulder Side ditch Crossing pipe Bridge Culvert

>95%

PROGRESS

Pavement

tav=100cm t=200mm >6ocm<t<77 t=150mm t=150mm 1st Seal=10/14 t=60mm t=40mm

Not specified

Ancillaries Structures

Page 95

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

7.3.6 Conclusions Regarding Design Parameters From the comprehensive and detailed analysis undertaken in Chapter 5 followed by the analysis done in the foregoing sections, it can be concluded that the cement treated geomaterials analyzed in this Study exhibit high safety factors and can certainly be adopted for the design and construction of the base course layers of the Airport Pavement.

7.3.7 Adopted Design Criteria The following standards and/or design criteria are thence mainly adopted in appropriation to the suitability, relevance and cost-effectiveness for the purposes of the design of the Songwe Airport Pavement Structure. 1. U.S. FAA : United States Federal Aviation Administration 2. ICAO: International Civil Aviation Organization

7.4 Evaluation of Air Traffic Volume and Growth Evaluation for traffic volume and growth was undertaken based on the US FAA Method. Considering an annual growth rate of approx. 4% over the design life of 20 years, Equivalent Annual Departures of 3,000 were adopted. 7.5 Engineering Analysis of Geomaterial Properties Comprehensive engineering analysis of the properties and characteristics of the existing soils and improved and/or selected geomaterials was undertaken in Chapter 5 of this Report.

7.6 Evaluation of Strength of Existing Subgrade 7.6.1 Relatively Stable Geomaterials Average subgrade CBR values were determined per location and the mean and section Design CBR values computed from the results presented in Chapter 5 of this Report. The subgrade is very stable and strong with CBR values greater than 50 on the average.

7.6.2 Analysis of Problematic and/or Expansive Soils No problematic soils were encountered within the Project area.

© 2009 Kensetsu Kaihatsu Limited

7.7 Determination of Pavement Structural Design 7.7.1 Determination of Total Pavement Thickness Required Subsequent to determining the Mean-section Design CBR values for the subgrade and the subbase (ref. to table 7.7.1), the weight on the main landing gear was determined from Fig. 7.2.4. Having pre-determined the design aircraft and the number of annual departures of the design aircraft, the design curves in Fig. 7.2.5 based on the U.S. Army Corps of Engineers Design Method S-77-1 and the U.S. FAA Design method, the total pavement thickness required were derived. Table 7.7.1 is a summary of the main design parameters that were adopted in determining the total pavement design thickness.

Page 96

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 7.7.1 Summary of Main Design Parameters Adopted
Design Aircraft Maximum Design Taxi Weight (kgs) 334,800 Weight on Main Landing Gear (kgs) 318,060 Number of Equivalent Annual Departures 3,000 Design CBR (%) Existing Subgrade 50 Existing Subbase 334 Design Life (yrs) Remarks

B747-100

20

Based on the data presented in Table 7.7.1, the Total Pavement Thickness required was determined from Fig. 7.2.5. The Total Pavement Thickness required is 7.4 inches or 188mm. Consequently, the design considers a Total Pavement Thickness of 200mm.

7.7.2 Thickness of Subbase The thickness, bearing capacity, strength and deformation resistance of the existing subbase were technically evaluated (ref. to Chapter 5) and determined to be more than adequate. Due to the coupled effects of cementation and Long Term Consolidation (LTC), the existing subbase exhibits very high bearing capacity and strength values (ref. to Section 5.3 of Chapter 5 of this Report). Consequently, 200mm is considered to be the combined thickness of the Base Course and Surface Course.

7.7.3 Thickness of Surface Course The thickness determined in the Original (existing) design of 100mm (40mm Wearing Course + 60mm Binder Course) was technically evaluated and found to be adequate (ref. to Subsection 7.8.1 and 7.8.2 of this Report). This thickness and configuration is therefore maintained as per the Original (Existing) Design.

7.7.4 Thickness of Base Course The thickness of the Base Course was computed by subtracting the thickness of the Surface Course from the combined thickness (i.e. 200-100mm) = 100mm.

© 2009 Kensetsu Kaihatsu Limited

The required thickness of the Base Course was therefore determined to be 100mm.

7.7.5 Thickness of Non-Critical Areas The total thickness of the original design for the non-critical areas was technically evaluated and found to be adequate (ref. to Chapter 5 of this Report). This thickness and configuration is therefore maintained as per the Original (Existing) Design.

Page 97

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

7.7.6 Typical Cross-section The Typical Cross-section of the Songwe Airport pavement structure designed in accordance with the U.S. Federal Aviation Administration (FAA) and the International Civil Aviation Organization (ICAO) Design Codes and stipulations is shown in Fig. 7.7.1.
TOPSOIL AND SEEDING SHOULDER RUNWAY SHOULDER TOPSOIL AND SEEDING

Fig. 7.7.1 Typical Cross-section based on US FAA / ICAO Design Methods

7.8 Comparison of Various Adequate Designs Under this section, a comparison of various options that were structurally considered to be adequate for the design aircraft and design life is presented. The main factors employed in undertaking this comparison are Structural Capacity Analysis, Deformation Resistance Analysis, Cost and Construction Time Savings.

7.8.1 Comparative Analysis of Structural Capacity

© 2009 Kensetsu Kaihatsu Limited

The �������� Method was adopted in computing and analyzing the structural capacity of the composite pavement structure. The value of �������� is calculated from the following equation.
�������� = ����1 ����1 + ����2 ����2 + ⋯ �������� �������� (7.1)

Where, ����1 , ����2 … �������� = Conversion Coefficient presented in Table 7.8.1. ����1 ����2 … �������� = Thickness of each pavement layer in cm. For a cost effective design for the Songwe Airport, the Target �������� including a global Safety Fator of 1.25 was determined to be (�������� ≅ 30) to cater for a projected Air Traffic for the B747-100 design aircraft and 3,000 Equivalent Annual Departures for a Design Life of 20 Years.

Page 98

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 7.8.1 Conversion Co-efficient for the Calculation of ��������
Pavement Course Method and Material of Construction Surface & Binder course Base Hot asphalt mix for surface and binder course Bituminous Stabilization Hot-mixed stability: 350kgf or more Cold mixed stability 250 kgf or more Cement Stabilization Lime stabilization Unconfined compression strength (7days): 30 kgf/cm
2

Conditions

Standard Coefficient, an

OPMC/GG Coefficient, an(OPMC)

1.00

GlasGRID Reinforced = 1.35

0.80

OPMC Level 10 = 0.94

0.55

8 = 0.86

0.55

OPMC Level 6 = 0.78

Unconfined compression 2 strength (10 days): 10kgf/cm Modified CBR value: 80 or more Modified CBR value: 80 or more Unconfined compression 2 strength (14 days) 12 kgf/cm or more Modified CBR value: 30 or more 20 to 30

0.45

OPMC Level 4 = 0.65: Cement/Lime Combination OPMC Level 2 = 0.58 OPMC Level 6 = 0.78

Crushed stone for mechanical stabilization Slag for mechanical stabilization Hydraulic slag

0.35 0.55

0.55

OPMC Level 6 = 0.78

Sub-base

Crusher-Run, slag, sand, etc

0.25 0.20

OPMC Level 2 = 0.58

Cement stabilization

Unconfined compression strength (7 days): 10kgf/cm
2

0.25

OPMC Level 4 = 0.65: Cement/Lime Combination

(Source: AASHTO, AAAC, Japan Road Association 1989 and XXIIRD PIARC World Road Congress, Paris 2007)

Notes: Conversion coefficients listed in Table 7.8.1 indicate the ratio of the thickness of the pavement by each method and material of construction to the thickness of hot asphalt mix for the binder and the surface courses

© 2009 Kensetsu Kaihatsu Limited

corresponding to the thickness of each material. Thus, the term a n Tn of Equation in 7.1 indicates the corresponding thickness of the n-th layer converted thickness of hot asphalt mix for the binder and surface courses. For example; 1 cm of pavement adopting mechanical stabilization corresponds to 0.35 of pavement adopting the hot asphalt mix method , and a 20cm of pavement using the hot asphalt mix method would therefore be (0.35×20=7). Also note the OPMC conversion Values determined empirically for varying OPMC Stabilization levels published in the XXIIRD PIARC World Road Congress, Paris 2007.

Page 99

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Structural Capacity of ORIGINAL (Existing) Design
TOPSOIL AND SEEDING SHOULDER RUNWAY SHOULDER TOPSOIL AND SEEDING

Fig. 7.8.1 Typical Cross-section of ORIGINAL (Existing) Design
�������� In this case the �������� is computed as: ����1 �������� = 1x10+0.8x15+0.35x15+0.25x20 = 32.25 > 30 [OK]

Structural Capacity of US FAA/ICAO Based Design
TOPSOIL AND SEEDING SHOULDER RUNWAY SHOULDER TOPSOIL AND SEEDING

© 2009 Kensetsu Kaihatsu Limited

Fig. 7.8.2 Typical Cross-section Based on US FAA / ICAO Design Methods
���������������� In this case the �������� is computed as: ���������������� �������� = 1x10+0.78x10+0.65x20 = 30.8 > 30 [OK]

Page 100

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

OPTION1 Structural Capacity of TYPE I PROPOSED Design

TOPSOIL AND SEEDING

SHOULDER

RUNWAY

SHOULDER

TOPSOIL AND SEEDING

Fig. 7.8.3 Typical Cross-section of Type I Proposed Design
����1 In this case the �������� is computed as: ����1 �������� = 1x10+0.78x15+0.78x15+0.65x20 = 46.4 »> 30 [OK]

OPTION2 Structural Capacity of TYPE II PROPOSED Design
TOPSOIL AND SEEDING SHOULDER RUNWAY SHOULDER TOPSOIL AND SEEDING

© 2009 Kensetsu Kaihatsu Limited

Fig. 7.8.4 Typical Cross-section of Type II Proposed Design
����2 In this case the �������� is computed as: ����2 �������� = 1x10+0.78x15+0.65x20 = 34.7 > 30 [OK]

Page 101

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

OPTION3 Structural Capacity of VE BASED Design
TOPSOIL AND SEEDING SHOULDER RUNWAY SHOULDER TOPSOIL AND SEEDING

Fig. 7.8.5 Typical Cross-section of Value Engineering (VE) Based Design In this case, the basic concept is that, owing to the high bearing capacity values that they exhibit, the Subbase is converted into a Base Course layer of 200mm and the Subgrade is converted into a subbase layer of 300mm.
����3 The �������� is therefore computed as: ����3 �������� = 1x10+0.65x20+0.35x30 = 33.5 > 30 [OK]

7.8.2 Comparative Analysis of Deformation Resistance Deformation Resistance is the ability of a founding structure, sub-structure or super-structue to resist the damaging effects imparted upon it under dynamic and/or static loading.

Analyses of the Deformation Resistance were undertaken by adopting empirically determined Elastic Modulus, ���������������� , which is basically defined as the modulus of elasticity within the linear elastic and recoverable range. In order to effectively characterize the deformation resistance of the composite pavement structure with varying layers under loading, the juxtaposed Full Depth Asphalt Concrete and �������� concept was applied. The resulting �������� is therefore computed based on the following equation.
�������� =
�������� �������� ������������ ������������3 + ������������ ������������ 1 1 3 �������� �������� + ������������ ������������ 1 3 �������� �������� + ������������ ������������ 1 3 �������� �������� + +�������� �������� 1 3 �������� �������� + �������� �������� 1 3 1 3

100 − �������� ������������3

© 2009 Kensetsu Kaihatsu Limited

�������� �������� �������� �������� �������� ������������ + ������������ + ������������ + ������������ + �������� + �������� + 100 − ��������

Where all thicknesses are expressed in cm and, ������������ = Thickness of Asphalt Concrete �������� ������������ = Thickness of Asphalt Treated Base Course �������� ������������ = Thickness of Crushed Aggregate Base Course �������� ������������ = Thickness of Cement Treated Base Course �������� �������� = Thickness of Granular Subbase �������� �������� = Thickness of Existing LTC Subbase ������������ = (100-�������� )=Thickness of Subgrade �������� �������� �������� �������� �������� �������� = ������������ + ������������ + ������������ + ������������ + �������� + �������� = Thickness of Pavement

Page 102

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Deformation Resistance of ORIGINAL (Existing) Design The schematic cross-section of the varying layers of the pavement structural configuration of the Original Design is shown in Fig. 7.8.6 below.

������������ =4,419MPa ������������ =4,419MPa �������� ������������ =3,635MPa �������� ������������ =2,872MPa
�������� �������� =2,080 MPa

Fig. 7.8.6 Schematic Cross-section of varying Layers of ORIGINAL (Existing) Design
����1 ��������

= =

10 × 16.41 + 15 × 15.38 + 15 × 14.21 + 20 × 15.38 + 40 × 15.38 100 164.1 + 230.7 + 213.2 + 255.4 + 615.2 100
3 3

3

= 14.79

����1 ∴ �������� =3,233MPa

Deformation Resistance of US FAA/ICAO Based Design The schematic cross-section of the varying layers of the pavement structural configuration of USFAA/ICAO Based Design is shown in Fig. 7.8.7 below.

������������ =4,419MPa ������������ =4,419MPa
�������� ������������ =7,357MPa �������� �������� =5,976 MPa

© 2009 Kensetsu Kaihatsu Limited

Fig. 7.8.7 Schematic Cross-section of varying Layers of US FAA / ICAO Based Design
����2 ��������

=

10 × 16.41 + 10 × 19.45 + 20 × 18.15 + 60 × 15.38 100
3

3

=

164.1 + 194.5 + 363 + 922.8 100
3

= 16.44

����2 ∴ �������� =4,447MPa

Page 103

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

OPTION1 Deformation Resistance of TYPE I PROPOSED Design The schematic cross-section of the varying layers of the pavement structural configuration of OPTION1 Type I Proposed Design is shown in Fig. 7.8.8 below.

������������ =4,419MPa ������������ =4,419MPa �������� ������������ =7,357MPa �������� ������������ =7,357MPa
�������� �������� =2,080 MPa

Fig. 7.8.8 Schematic Cross-section of varying Layers of Type I Proposed Design

����3 �������� =

10 × 16.41 + 15 × 19.45 + 15 × 19.45 + 20 × 18.15 + 40 × 15.38 100
3

3

164.1 + 291.8 + 291.8 + 363 + 615.2 = 100 = 17.26
3

����3 ∴ �������� =5,141MPa

OPTION2 Deformation Resistance of TYPE II PROPOSED Design The schematic cross-section of the varying layers of the pavement structural configuration of OPTION2 Type II Design is shown in Fig. 7.8.9 below.

������������ =4,419MPa ������������ =4,419MPa
�������� ������������ =7,357MPa �������� �������� =5,976MPa

© 2009 Kensetsu Kaihatsu Limited

Fig. 7.8.9 Schematic Cross-section of varying Layers of Type II Design

����6 �������� =

10 × 16.41 + 15 × 19.45 + 20 × 18.15 + 55 × 15.38 100
3

3

164.1 + 291.8 + 363 + 845.9 = 100 = 16.65
3

����6 ∴ �������� =4,614MPa

Page 104

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

OPTION3 Deformation Resistance of VE Based Design The schematic cross-section of the varying layers of the pavement structural configuration of OPTION3 VE Based Design is shown in Fig. 7.8.10 below.

������������ =4,419MPa ������������ =4,419MPa
�������� �������� =5,976MPa

�������� =3,641MPa
Fig. 7.8.10 Schematic Cross-section of varying Layers of Value Engineering (VE) Based Design
����4 ��������

=

10 × 16.41 + 20 × 18.15 + 30 × 15.38 + 40 × 15.38 100
3

3

=

164.1 + 363 + 461.4 + 615.2 100
3

= 16.04

����4 ∴ �������� =4,125MPa

7.8.3 Cost Comparative Analysis A summary of the costs between the Original Design costs and the Reviewed Design costs is presented in Table 7.8.2 for each pavement layer, whilst a graphical representation of the same is depicted in the chart in Fig. 7.8.11. Table 7.8.2 Summary of Comparison of Costs
Construction Costs (TZ, TShs) BoQ Pavement Layer Item No. 103 Crushed Aggregate Base Course (150mm) Runway Crushed Aggregate Base Course (150mm) Taxiway Crushed Aggregate Base Course (150mm) Parking Area Crushed Aggregate Base Course (150mm) Connector Roads 104 Cement Treated Base Course for Runway and Taxiway (2×150mm), including Parking Area and Connector Roads 105 Asphalt Trreated Base Course (150mm) for Runway and Taxiway TOTAL Without Design Review [ORIGINAL] (1) 1,470,150,000 62,055,000 123,750,000 With Design Review [TYPE I] (2) 0 0 0 Difference (3)=(1)-(2) With Design Review [TYPE II] (4) 0 0 0 Difference (5)=(1)-(4) Remarks

1,470,150,000 62,055,000 123,750,000

1,470,150,000 62,055,000 123,750,000

© 2009 Kensetsu Kaihatsu Limited

129,195,000

0

129,195,000

0

129,195,000

0 4,861,350,000

-4,861,350,000 2,975,250,000

-2,975,250,000

5,029,600,000

0

5,029,600,000

0

5,029,600,000

6,814,750,000 4,861,350,000

1,953,400,000 2,975,250,000

3,839,500,000

Page 105

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Fig. 7.8.11 Graphical depiction of summarized comparison of Maintenance Costs
Comparison of the ORIGINAL (Existing) Design and the REVIEWED Design Type I indicates that a substantial savings of 29% (TShs1,953,400,000) will be realized by adopting the REVIEWED Design Type I. The computational results further show that the Reviewed Design Type II will culminate in tremendous cost savings of 56% (TShs. 3,839,500,000)

7.8.4 Construction Time Comparative Analysis Comparative analysis of the construction time that would be required is made for the Original (Existing) Design and the Proposed Type I Design. Note that the comparison is made with respect to only the crushing time required for the crushed aggregates quantified in the Original (Existing) Design. A summary of the computations is presented in the tabulation format below. (1) Original Design
Volume of Crushed Aggregate Base Course Material (150mm) for Runway Volume of Crushed Aggregate Base Course Material (150mm) for Taxiway Volume of Crushed Aggregate Base Course Material (150mm) for Parking Area Volume of Crushed Aggregate Base Course Material (150mm) for Connector Roads Volume of Crushed Aggregate for Asphalt Treated Base Course Material (150mm) for Runway and Taxiway Only = 32,670m
3

=

1,379m

3

=

2,750m

3

=

2,871m
3

3

= = = = =

25,148m

© 2009 Kensetsu Kaihatsu Limited

Total Volume of Material Required Weight of Aggregate Required Add 10% for loss Total Weight of Aggregate Assuming a Crushing Rate of 70m /Hr. and crushing time of 12Hrs/Day 3 Tonnage Crushing/Day = 70m x 12Hrs = No. of days required for Crushing
3

64,818m

3

64,818m x 2.5 0.1 178,250 Tons X

3

=162,045 Tons 162,045 = 16,205 Tons

(Approximately 180,000 Tons)

840Tons = 180,000 / 840 = 214 days (7Months)

Page 106

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

(2) Reviewed (Proposed) Design Type I
Volume of Base Course Material to be Proccessed Approximate Rate of Proccessing per Day No. of days required = = = 64,818m 2,500m 65,000m
3

(65,000m )

3

3

3

/2,500m

3

= 26days

Considering logistics and other cirumstancial prevalences, construction of the Reviewed (Proposed) Design Base Courses may take approximately 2Months. As can be noted the Reviewed Designs will realize appreciable savings in construction time mainly in terms of reduction in crushing time. Early completion will certainly be a major cost-benefit component to the Employer and users.

7.8.5 Derivative Comparison (1) Costs From Table 7.8.1 and Fig. 7.8.8 it can be noted as follows:(iii) (iv) WITHOUT Design Review [Original Design] is the more expensive than both TYPE I and TYPE II Reviewed Designs. In comparison to WITHOUT Review [Original Design], WITH Type I Reviewed Design cost savings of TShs TShs1,953,400,000/= (approx. 1.9B) are realized, while WITH Type II Reviewed Design cost savings of TShs 3,839,500,000/= (approx. 3.8B) are made.

(2) Structural Capacity Table 7.8.3 presents a comparison of the structural capacity levels of the various designs. Table 7.8.3 Structural Capacities based on �������� Values for varying Designs (Target �������� Value = 30)
Original (Existing) Design 32.25 USFAA/ICAO Design OPTION1 Type I Proposed Design 46.4 OPTION2 Type II Proposed Design 34.7 OPTION3 VE Based Design Remarks

30.8

33.5

© 2009 Kensetsu Kaihatsu Limited

Based on the computations made in Sub-section 7.8.1, it can be noted that the Proposed Designs (both Type I and Type II) exhibit the highest Structural Capacity.

(3) Deformation Resistance A comparison of the Deformation Resistance of varying Designs is given in Table 7.8.3. Table 7.8.3 Comparison of Deformation Resistance Based on Elastic Modulus for Varying Designs
OPTION1 Original (Existing) Design 3,233 OPTION2 USFAA/ICAO Design 4,447 OPTION1 Type I Proposed Design 5,141 OPTION2 Type II Proposed Design 4,614 OPTION3 VE Based Design Remarks

4,125

Page 107

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

The analysis carried out in Sub-section 7.8.2 which are summarized in Table 7.8.3 indicate that, in comparison to the Original (Existing) Design, the Proposed (Reviewed) Designs enhance the Deformation Resistance by tremendously. It can be noted that, in terms of Deformation Resistance, Type I proposed design is superior to the Original (Existing) Design by 59%, while Type II proposed design exceeds the Original by 43%. This is attributable mainly to the cementatious nature of the Base Course material proposed.

(4) Construction Time This is computationally demonstrated in Sub-section 7.8.4.

7.8.6 Comparative Conclusions In undertaking the foregoing analysis, the impact of environmental factors was taken into consideration (ref. to Chapter 4). It can be noted that not only do both Type I and Type II Proposed (Reviewed) Designs realize enormous Cost-savings but they also enhance the Structural Capacity (Bearing Capacity, Strength, Serviceability) and Deformation Resistance of the Pavement Structure. It can also be noted that these Designs can be implemented within a very short period (Approx. 70% less construction time) in comparison to the Original (Existing) Design.

© 2009 Kensetsu Kaihatsu Limited

Page 108

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

CHAPTER 8 8. ANALYSIS OF TIME DEPENDENT STRUCTURAL SOUNDNESS 8.1 Analysis of Structural Capacity Deterioration with Time Progression based on the SCDR Model

8.1.1 Definition of Structural Failures Distinctively, there are two different types of pavement failure. The Structural Failure includes a collapse of the pavement structure or a breakdown of one or more of the pavement components of such magnitude to make the pavement incapable of sustaining the loads imposed upon its surface and through the pavement structure. The second type is classified as Functional Failure and may or may not be accompanied by structural failure but is such that the pavement will not carry out its intended function without causing discomfort to passengers or without causing high stresses in the vehicle that passes over it due to roughness. Obviously the degree of distress for both categories is gradational, and the severity of distress of any pavement is largely a matter of opinion of the person observing the distress. As an example, consider a rigid pavement that has been resurfaced with an asphaltic overlay. The surface may develop rough spots as a result of breakup in the bituminous overlay (functional failure) without structural breakdown of the overall structure. On the other hand, the same pavement may crack and break up as a result of overload (structural failure). Maintenance measures for the first situation may consist of resurfacing to restore smooth – riding qualities to the pavement. However, the structural type of failure may require complete rebuilding/reconstruction. 8.1.2 Fundamental Theories/Concepts Applied in Developing SCDR Model (1) Theories and/or Concepts Considered The choice of an effective analytical method depends predominantly on the choice of the backbone engineering theories, principles and concepts and the extent to which they translate to pragmatic application. For these purposes, the theories and concepts applied are based on fundamental theories, principles and concepts introduced in Chapter 4. The generalized equation of the existing road conditions can be expressed as a function of loading conditions, pavement type (structurally), pavement layer quality, structural thickness as well as intrinsic material properties depicted in Equation 8.1.
v Rc  f df , ti , Pc , Pe , te,  ms





(8.1)

Where,

Rc = road condition, df = dynamic load factor, t i = response mode factor of layer of the pavement
v structure, Pc = pavement configuration, Pe = pavement layer quality, t e = structural thickness,  ms =

parameter delineating moisture – suction variation. On the other hand, the extent of distress of deformation can be derived based on the theories introduced in the preceding sections applied for carrying out back analysis of the deformation history of a distressed pavement structure. In a generalized state, this can be expressed as shown in Equation 8.2.

© 2009 Kensetsu Kaihatsu Limited

 dh  f  ' , ' , p'oc , qoc ,  'oc , f yi ,  ijo  f f f
where,

(8.2)

 dh =

parameter delineating deformation history  ' = consolidation stress ratio,  ' = modifier
oc oc

between Isotropic and Anisotropic stress paths, p' f , q f = invariant stress under over consolidation conditions,

 ,f = Angle of Internal Friction within the failure zone.

Page 109

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

The following theories, concepts and equations are then employed as the inputs for the generalized state model.  Dynamic Loading Effects Although the equivalency law and hence the fourth power law equations developed at the AASHO road test incorporate actual dynamic load effects based on measurements of the overall loss of serviceability that included dynamic components, attempts to modify these equations have constantly been made. In this case, the equation proposed by Eisenmann (1975) containing a quantifier, known as pavement structure stress factor, is applied. This equation is adopted because it is considered to be the best mathematical representation of the theory of serial basins. In this relation, it is assumed that dynamic wheel forces are Gaussian, i.e. normal distributions. The value deduced of the fourth power of instantaneous wheel force is given by:
4   E p t 4 = 1  6CV2  3CV4 PSt

 

(8.3)

where, P(t) = instantaneous tyre force at time t, Pst = E[p(t)] = static (average) tyre force, Cv = coefficient of varieties of dynamic tyre force and E[ ]= expection operator. Eisenmann (1978) further modified Eq. (8.3) to account for the effects of wheel configuration and tyre pressure in the form of Eq. (8.4)

    III Pst . 4

(8.4)

where,  = 1+6 CV +3 CV (dynamic oil drilling pad factor),  I = parameter accounting for wheel
2 4

configuration for both single or dual tyres and  II = parameter accounting for tyre contact pressures. Intuitively,  and ’ are dynamic versions related to the AASHO load equivalent factor (LEF) in the forms: K = vLEF and, k    V  I  II  LEF,
4

(8.5)

k = ( Pst . )-4

 Transversal Propagation of Stress Induced Waves The concept of serial deflection basins is introduced by considering the dynamic wheel load concept. It is assumed that the deflection basins formulated can be mathematically represented by the

© 2009 Kensetsu Kaihatsu Limited

damping effects of the pavement layers either in a composite or independent form. The damped oscillatory equation of motion is therefore adopted.
2  rd  coeht sin h2  0  t  o 0.5





(8.6)

where,

 rd = rebound deflection, Co= constant representing the initial conditions of loading,

d=damping factor of the pad foundation structure related to layer stiffness, t = response time

Page 110

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

measured,  = angular frequency and  = constant representing the initial position and condition of deflection measurement.

The concept of energy was also applied in analyzing the curvature of the deflection basin in relation to the elastic moduli energy equation, expressed as follows.

E(t )  0.5C02 e 2ht  a w02  h 2 Cos 2 w02  h 2











0.5

t   0  f r sin 2 w02  h 2







0.5

t  0



(8.7)

where, fr is the force constant and la=axle load. It is further considered that the energy decreased exponentially with the increase in time and is expressed as:

dE (t ) d 2  1 / 2 a  rd  1 / 2 f r  2 dt dt





(8.8)

 Theory Of Applying Excitation Truck And Vibration Roller The excitation truck and vibration roller were used for purposes of studying the impact and magnitude of disturbance on the quantities of the deflections measured, longitudinal deformation, transversal rebound characteristics and total pavement structural response. Effects of the variation of the speed of the excitation and vibration modes of the vibration roller are quantitatively analyzed from the following relation of steady state motion, completely specified by an amplitude b and phase angle  .

For low driving frequencies, the phase angle is expressed as:

  arctan
© 2009 Kensetsu Kaihatsu Limited



2 h 0   2
2 0



(8.9)

In this case the driving force and resulting deflection are in phase hence the amplitude is expressed as:

b



2 0

 w 2   4h 2 2

f0



0.5

(8.10)

For high driving frequencies the amplitude is considered to be

Page 111

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

b



f0
4

 4h 2 2



0.5

(8.11)

In cases whereby d is small for light damping then:

b

f0

2

(8.12)

The phase angle is then given by

  arctan



2hw    2
2 0



(8.13)

In such a case as the frequency of  of the impressed force is increased, the amplitude decreases and the phase angle tends towards   Shear Wave Propagation Through Pad Foundation Layers The analysis of the shear wave propagation through pavement structural layers is carried out by applying the concepts related to the linear (LIN) and equivalent linear (EQL) methods. These methods of analysis are commonly made by multiple reflection of vertically propagating horizontal components of shear waves though multiple layered profile one dimensional system Assuming the deflection at any layer n is given by

 rd   rd Z 1t    rd Z e iwt
where,  rd is the total displacement .The equation of motion is then given by:

(8.14)

© 2009 Kensetsu Kaihatsu Limited

n

n  2 rd  2 n  3 n  Gn  n t 2 Z 2 Z 2 t

(8.15)

where,  n  2G n hn ,   density of pad foundation layer, G = shear modulus and h is damping.

The solution of the resulting differential equation for the steady state harmonic motion is obtained as follows:

Page 112

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009
nrd     n e ik n Z  Fn e  ik n Z

(8.16)

and,

 n    ik n G n E n e ik Z  Fm e  ik Z 
n n

(8.17)

where, by

kn  

pn Gn

(8.18)

Where, 

m

= shear stress at layer n, kn = wave number layer n and En and Fn are amplitudes of the

upwards and downwards bound waves.

Applying the conditions of continuity at the interface of the layers and the condition that shear stress at the surface is zero, yielding E1=F1, then the transfer function between any layer can be quantified as:

Anm   

en    f n   en    f n  

(8.19)

where, Anm = transfer function between layers n and m, e n   =

En

E1

and f n 

Fm

F1

. These

facilities the analysis of the unknown motion in other layers provided that the transfer function and input motion at the layers are known. Consequently the acceleration and the strain can be computed from the deflection functions expressed as:
i  K n  t  2 n   n Z t     rd  2  ne  rd 1  2  i  K Z  w t  t  Fne n   

© 2009 Kensetsu Kaihatsu Limited

(8.20)

and ,
n  n ei  K n  t     2 rd  ikn   i  K Z  wt     Fn e n   

n 

(8.21)

Page 113

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

n where, rd = acceleration in layers n and

 n =strain in layer n. Detailed description of the theoretical

background and analytical procedure are discussed by Kanai (1951) Haskeu (1953) Schnabel (1971) and Kanai (1983).  Correlation of Response Time to Elastic Properties. Wave propagation techniques are usually used to determine the elastic modulus of in-situ geomaterials. In applying this method a common assumption is that the material behaves as a linear elastic material under isotropic conditions. Based upon such theoretical consideration, the models of the material can be determined from the following equation.

  21     2  s  

n 
g 

(8.21)

where, E= Elastic modulus

 = poisson’s ratio (values of 0.4 for asphalt concrete and 0.45 for aggregate

base and subgrade) proposed by the Asphalt Institute were adopted in these analysis, Vs= shear wave velocity

 n = density of layer n and g = acceleration of gravity.

In this study, it was assumed that since Vs= Lf where, L= the wavelength and f=frequency them Vs  tr (response time). Measured values of t were then used in computing the layer depth to determine the responsive layer and estimate the corresponding elastic modulus. 

Back Analysis of Distressed Pad Foundation Deformation History.

The Constitutive model on cyclic plasticity for geomaterials based on non-linear kinematic hardening theory proposed by Yashima et al. (1994) is adopted in attempting to back analyze the deformation history of the pad foundation structure. This model was chosen because of it’s incorporation of the non-linear kinematics hardening rule. When incorporated into an overstress type of model, it is found to be effective in expressing the changes in retardation in the strain rate direction upon a

© 2009 Kensetsu Kaihatsu Limited

corresponding change in the direction of the stress. Furthermore this model is found to reproduce to an appreciable extent, the plastic damage during cyclic or repeated loading. By taking into account the effects of sub grade layer material into the sub base, the constitutive model for clay is adopted in simulating the composite yield characteristics of these layers, while the distress behavior of the upper pad foundation consisting of the unbound crushed aggregate base course and the asphalt concrete, are analyzed by modifying the theories in the constitutive model for soft rock.

Page 114

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

 Constitutive model applied for lower pad foundation layers The viscoplastic model for over consolidated clay extended to a cyclic model by Oka (1988) is applied. The static yield functions that account for changes in the stress ratio are given as follows:

* * * * f y1  ij  xij ij  xij







1

2

 RD1  0

(8.22)

where, RD1 = parameter defining the elastic region and xij =the kinematics hardening tensor. By introducing the non linearity of the kinematics hardening, xij can be written as
* vp dxij  B1* A1* deij  xij d vp 

*

*

(8.23)

* In which A1 and B1 are the material constants and deij is the increment of the viscoplastic deviatoric

*

*

strain. The second invariant of the increment of the plastic deviatoric strain is derived as:

vp vp d vp  deij deij





1

2

(8.24)

For the first yield function, the plastic potential is assumed to be:

* * * * g1   ij  xij  ij  xij





~ ' 12  M *1n  m

'  ma (1)   0  

(8.25a)

where,

'  ma(1) = material parameter and M * is the stress ratio when the layers are under maximum

~

compression condition: Considering the over consolidated boundary surface between the NC and OC zones to be expressed as:

© 2009 Kensetsu Kaihatsu Limited

~* ' ' fb  *   M m1n  m  ma(1)  0 0





(8.25b)

* In the NC Zone  f b 0 , M * is kept constant i.e., M * = M m whereas in the OC region, it is defined as:

~

~

~

~  fb  0 , M * is defined as:
~ ' ' M *    n  m  mc 

(8.26)

Page 115

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

where, the current stress ratio   ijij
* *



*



1

2

' ' * and  mc   mb exp ( *0  / M m )

 Estimation of Consolidation and Shear Stress Paths The input parameters for the constitutive model introduced in the preceding section were derived from the following theories and concepts. As the repeated loading progresses, the cumulative effects are back analyzed by applying the concepts of consolidation and shear stress ratio functions under normally consolidated (NC) conditions introduced by Mukabi and Tatsuoka (1996) and Mukabi (2001d). In so doing, the initial stresses are computed from the experimental results of full scale trial sections (Mukabi, 2002; Gono et al., 2003, this conference) .The cumulative stresses are then derived by considering the average loading rate and cumulative repeated loading over a given period of time. Once the maximum deviator and mean effective stresses are determined, the stress ratio functions, defined from the following expressions proposed by Mukabi and Tatsuoka (1999b) and Mukabi (2001d) are applied.

   A  CSR  B

(8.27)

Where, A and B are material properties, and the consolidation stress ratio function independent of the effects of loading rate, is derived from the relation 

 CSR , which is
, whereby  ' =

1
~

CSR

qmax
I

function of normalized angle of internal friction expressed as  '   / Q (A: An isotropic I:
A

Isotropic) and qm ax = maximum deviator stress.  ' can be determined from the quasi-emprical equation (Mukabi, 2001d) expressed in general form as:

 '   SR  SR /  SR

(8.28)

Where, ASR and BSR are stress ratio constants and  SR  q p ' is the invariant stress ratio variable.

© 2009 Kensetsu Kaihatsu Limited

The antistrophic stress path is derived from the isotropic one by introducing a modifier proposed by Mukabi and Tatsuoka (1999b) expressed as:

 

K I     CSR .CSR

m ax I

(8.29)

Page 116

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

where,  m ax = (q/p’) at qmax, KI=1 and CSR= consolidations stress ratio. The modifier is applied in the relation q   p .

On the other hand, the invariant stresses and angle of internal friction under over consolidated (OC) condition were derived from the flowing correlations proposed by Mukabi (2001d).

oc qmax 

KoNC

NC K oNC .qmax oc  Ko . A .CSR NC

(8.30)

OC OC where, K Ox  KOx  OCR

sin  'f

and
OC KOx  1  sin  ' f

The corresponding mean effective stress, p f

'OC

and angle of internal friction  f

'OC

are given by:

q

'OC f

NC   PC'OC  Pf' NC KO   NC  OC NC  ' pCNC  K O  K O . A CSR   

(8.31)

and ,



'OC f

NC ' NC   KO   NC   f OC NC  KO  KO . A CSR   

1

(8.32)

 Constitutive Model Applied for Upper Pad Foundation Layers Adachi and Oka (1992) proposed that the stress history tensor is a function of the effective stress

© 2009 Kensetsu Kaihatsu Limited

history with respect of the strain measure. This history tensor,

 ijO*' is given by

O (  ij *' 

1 Z  0 exp Z  Z ' /   ij' Z 'dZ ' T

(8.33)

where, dz= deij deij





1

2

, Z = strain measure, T=material parameter which controls the strain-hardening

and strain-softening phenomena and deij is the increment of deviator strain tensor.

Page 117

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

The plastic potential is assumed to be:

' 1 ~   b  * * * *  g 1   ij  xij  ij  xij  2  M * 1n  'm  b   0  mb 

(8.34)

The OC boundary is given as :

~*  ' b  f b  *   M m1n  'm 0   b   0   mb 

(8.35)

The OC region is therefore defined as:

 ' b  ~ M *     n  'm   b    mb 

(8.36)

Figure 8.1.1 Depiction of Determining Period and Level of Maintenance Based on the SCDR Model 8.1.3 Analysis of Structural Capacity

© 2009 Kensetsu Kaihatsu Limited

1) Initial Structural Capacity It is imperative, when undertaking the design of flexible-pavement structures, to consider factors such as subgrade characteristics, pavement layer strength and conditions, load and traffic parameters, environmental conditions as well as the economics of design and construction. Some of the major factors that affect the status or condition of a pavement structure include the Relative Damaging Effect (RDeff.), which is related to the ESAL, variation in quality of materials prompted by environmental factors, deterioration in pavement layer thickness through loss of aggregates and infiltration of inferior lower quality materials into the upper layers of the pavement structure.

Page 118

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

The concept of remaining life can be transposed or defined in terms of the existing structural capacity by application of the following equation.
e Re f SC  f RL  f SC  RDeff . x rf





(8.37)

Re Re Where f SC represents the existing structural capacity, f RL = Remaining Life Factor, f SC = Structural Capacity

Re Factor of a newly constructed or reconstructed pavement structure in which case f SC =1 and RD eff . = 0.298 is

the damaging factor while  rf = defines contribution of a multitude of factors affecting the magnitude of the damaging effect defined as:

 rf   PSF x RSF x PSI
where △PSF= Present Serviceability Factor, △RSF = Redundant Serviceability Factor and △PSI = Present Serviceability Index computed as △PSI=3.34 for this Project Road and △PSF = 0.18, whereas △RSF is derived from the expression

 RSF  1  0.01C fAC  FCAC xC BC  FCBC xC SB  FCSB  f f

(8.38)

C fAC , C BC and C SB are conversion factors for Asphalt Concrete, Base Course and Subbase respectively, while f f
FCAC , FCBC and FCSB are correction factors related to the deterioration of pavement layer thickness. In the
AC BC SB case of a newly or reconstructed pavement structure, it is assumed the FC , FC and FC = 1. However,

based on the SCDR Model, the time dependent deterioration structural factor can only be computed where Nt > 2.2 years. Considering structural and stability safety factors as well as quality control deficiencies during construction, the initial structural capacity factor defined at Nt=2.2 years is computed as below for design parameters determined as per standard specifications. △ Hence,
e( t f SC (Nst2.2 =1-0.613 )
rf

= 0.18x1.019x3.34 = 0.613



e( t f SC (Nst2.2 =0.824 )

While, for geomaterials exhibiting enhanced engineering properties, △RSF = 0 hence △rf = 0, consequently,

© 2009 Kensetsu Kaihatsu Limited

e( t  f SC (Nen)2.2 =1

2) Deterioration of Structural Capacity with Time Progression Some of the major factors that contribute to the deficiency with time, of the structural capacity and serviceability level of an existing pavement structure were mentioned in the preceding Sub-Section 8.1.2. This deterioration with time is known to grossly affect the performance of pavement structures. t The deterioration with time of the structural capacity factor f SC after Nt = 2.2 years can be defined by Eq. (8.39) below,

Page 119

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

t e f SC  f SC x log N t1.5





1

(8.39)

Based on the foregoing concepts and equations, the following equation is applied for soft clayey soils.

f t SC  ASC N t  BSC N t  C SC
Where,

(8.40)

f t SC  Time dependent Structural Capacity Factor

ASC  0.001, BSC  0.0507 and C SC  1.13 are Structural Capacity~Time related constants
N t  Time Progression in Years
On the hand, for OPMC, mechanically and/or chemically (treated) stabililized geomaterial, stiff soils and relatively hard rock, the following equation is applied.
−���� ����.������������������������ ���� �������� ��������

�������� = �������� × ����������������.�������� �������� �������� ����

× ���� +

× ℮����.����������������

(8.41)

���� �������������������� ������������ = ������������������������������������ ���������������������������������������� �������������������������������� ���������������� �������� = 2.2��������������������

3) Analysis of Influence of Environmental Factors Environmental factors such as moisture-suction variation due to seasonal cycles, inferior material intrusion as a result of the combined effects of dynamic loading and water infiltration (pumping) and land use affecting the structural pavement layer thickness are known to affect the structural capacity and serviceability levels of a pavement structure. In order to determine in a quantitative manner, the magnitude of the influence of these factors in relation to the depreciation (deterioration) of the structural capacity of a pavement structure, the following equations are adopted. ���� The environmental factors time dependant generalized equation is factored as ������������ and expressed as, �������� = ℮ ����.�������������������� �������� ��������
����

−����

(8.42)

���� The environmental factors time dependant depreciating variation factor, ������������ is defined as,

�������� = �������� × �������� × �������� ������������ ������������. �������� �������� Where, �������� = Moisture~Suction Depreciating Factor ������������ �������� = Inferior Material Intrusion Depreciating Factor ������������ �������� = Pavement Layer Thickness Depreciating Factor �������� The time dependant Structural Capacity depreciating factor is therefore computed as, �������� = �������� × �������� �������� �������� �������� �������� = Structural Capacity Depreciation Factor �������� �������� = Initial Structural Capacity (pre-consolidation) �������� �������� = Time Progression in Years �������� = 2.2years (Reference Time Period) ���� �������� = 0.824 (Reference Structural Capacity Factor) ��������

(8.43)

© 2009 Kensetsu Kaihatsu Limited

(8.44)

Page 120

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

8.2 Analysis of Time Dependent Structural Capacity for Varying Designs of Songwe Airport In this Study, five (5) pavement designs have been considered. These designs are presented in Chapter 7 of this Report. In order to arrive at the most optimum VE based conclusion and recommendation, it is considered vital to incorporate the element of maintenance period and costs accordingly. The appropriate periods and modes of maintenance are determined in terms of a direct proportional relationship between maintenance needs and costs to the deterioration of the pavement structural capacity with time progression. Table 8.2.1 is a summary of the main parameters that are adopted in carrying out these analyses for the various designs considered Table 8.2.1 Summary of Main Parameters Adopted for Analysis for Varying Designs
Option Type Layer Type CBR (%) qu (MPa) Emax Main Analysis Parameters �������� (εa)ELS x �������� �������� 10-3 (%) 0.8313 32.25 0.72 1.0045 30.8 0.87 1.1546 46.4 1.00 1.0391 34.7 0.90 0.9237 33.5 0.80 ���������������� ����������������. ������������

ORIGINAL USFAA/ICAO OPTION1 OPTION2 OPTION3

Composite Composite Composite Composite Composite

161 195 224 202 179

3.90 4.71 5.42 4.80 4.34

3,233 4,477 5,141 4,614 4125

1 1 1 1 1

1 1 1 1 1

1 1 1 1 1

Notes:
          CBR : California Bearing Ratio applied for Composite Base Course, Subbase and Subgrade only �������� : Unconfined Compressive Strength ���������������� : Elastic (Young’s) Modulus �������� ������������ : Elastic Limit Strain �������� : Structural Pavement Thickness Indicator ���� ������������ : Initial Structural Capacity Ratio ���� �������� : Moisture-Suction Depreciating Factor ���� ���������������� : Inferior Material Intrusion Depreciating Factor ������������ : Pavement Layer Thickness Depreciating Factor All parameters are considered the initial parameters that are determined during the Virgin Loading stage.

© 2009 Kensetsu Kaihatsu Limited

In undertaking these analyses, the effects of consolidation in enhancing the bearing capacity, strength and deformation resistance during the first period of dynamic and static loading have not been taken into consideration. Tables 8.2.2 to 8.2.8 are a summary of the deterioration factors and depletion of the structural capacity for the varying designs, while Figs. 8.2.1 to 8.2.7 are a graphical depiction of the corresponding trend of the structural capacity with the progression of time. In this case, the computations postulate scenarios of “WITH MAINTENANCE” scenario where only consistent routine and periodic maintenance are undertaken without full scale recarpeting (resurfacing) and “WITHOUT MAINTENANCE” scenario whereby full scale recarpeting (resurfacing) would then become necessary at prior to the expiry of the Design Life.

Page 121

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 8.2.2 Structural Depreciation Factor for ORIGINAL Design option.

Resulting TA With Maintenance Vs. Time
35 30 25
Resulting TA

Resulting TA WithOUT Maintenance Vs. Time
35
30 25

20 15 10 5

Resulting TA
0 2 4 6 8 10 12 14 16 18 20 22

20 15 10 5

© 2009 Kensetsu Kaihatsu Limited

0 Time Progression, Nt (years)

0 0 2 4 6 8 10 12 14 16 18 20 22
Time Progression, Nt (years)

Figure 8.2.1 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting �������� “WITH Maintenance” Scenario as well as “WithOUT Maintenance” effect for ORIGINAL Design

Page 122

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 8.2.3 Structural Depreciation Factor for U.S. FAA – ICAO Based Design option.

Resulting TA With Maintenance Vs. Time
35 30 25
Resulting TA

Resulting TA WithOUT Maintenance Vs. Time
35 30 25
Resulting TA

20 15 10

20 15 10 5 0

© 2009 Kensetsu Kaihatsu Limited

5 0 0 2 4 6 8 10 12 14 16 18 20 22 Time Progression, Nt (years)

0

2

4

6

8

10

12

14

16

18

20

22

Time Progression, Nt (years)

Figure 8.2.2 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting �������� “WITH Maintenance” Scenario as well as “WithOUT Maintenance” effect for USFAA-ICAO Design

Page 123

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 8.2.4 Structural Depreciation Factor for OPTION1 Proposed Type I Design

Resulting TA With Maintenance Vs. Time
50
45

Resulting TA WithOUT Maintenance Vs. Time
50 45 40 35

40 35

Resulting TA

25 20 15 10 5 0 0 2 4 6 8 10 12 14 16 18 20 22 Time Progression, Nt (years)

Resulting TA

30

30 25 20 15 10
5

© 2009 Kensetsu Kaihatsu Limited

0 0 2 4 6 8 10 12 14 16 18 20 22 Time Progression, Nt (years)

Figure 8.2.3 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting �������� “WITH Maintenance” Scenario as well as “WithOUT Maintenance” effect for OPTION1 Type I Design

Page 124

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 8.2.5 Structural Depreciation Factor for OPTION2 Proposed Type II Design

Resulting TA With Maintenance Vs. Time
40 35 30 25 40 35 30
25

Resulting TA WithOUT Maintenance Vs. Time

© 2009 Kensetsu Kaihatsu Limited

Resulting TA

20 15 10 5 0 0 2 4 6 8 10 12 14 16 18 20 22 Time Progression, Nt (years)

Resulting TA

20
15

10 5 0 0 2 4 6 8 10 12 14 16 18 20 22 Time Progression, Nt (years)

Figure 8.2.4 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting �������� “WITH Maintenance” Scenario as well as “WithOUT Maintenance” effect for OPTION2 Type II Design

Page 125

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 8.2.6 Structural Depreciation Factor for OPTION3 VE Based Design

Resulting TA With Maintenance Vs. Time
40
35

Resulting TA WithOUT Maintenance Vs. Time
35

30

30 25

25

© 2009 Kensetsu Kaihatsu Limited

Resulting TA

Resulting TA

20

20 15

15

10 10 5 0 0 2 4 6 8 10 12 14 16 18 20 22 Time Progression, Nt (years) 5

0

0

2

4

6

8

10

12

14

16

18

20

22

Time Progression, Nt (years)

Figure 8.2.5 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting �������� “WITH Maintenance” Scenario as well as “WithOUT Maintenance” effect for OPTION3 VE Based Design

Page 126

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Table 8.2.8 is a summary of the structural capacity depreciation factor, while Fig. 8.2.7 depicts the characteristic trends of the structural capacity depreciation with time progression over the design life for varying design options. Table 8.2.8 Structural Depreciation Factor with Time Progression for Varying Design Options

50
45

Resulting TA WITH Maintenance vs. Time
Original USFAA/ ICAO

50 45

Resulting TA WithOUT Maintenance vs. Time
ORIGINAL
USFAA/ ICAO OPTION1 Proposed Type I

OPTION1 : Proposed Type I

40 35
Resulting TA
30

OPTION2 : Proposed Type II
OPTION3: VE Based

40 35
30

OPTION2 Proposed Type II
OPTION3 VE Based

Resulting TA

Range of Design Criteria 25
20 15

25 20

Range of Design Criteria

Critical Line

Critical Line

15 10
5 0

10
5 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Time Progression, Nt (years)

0

1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16 17 18 19 20 21 22

Time Progression, Nt (years)

1.1
1.0

Depreciated Structural Capacity Factor vs. Time "WithOUT Maintenance" ORIGINAL
USFAA/ ICAO OPTION1 Proposed Type I OPTION2 : Proposed Type II

1.1

Structural Depreciation Factor Vs. Time Progression "WITH Maintenance" ORIGINAL USAFAA/ICAO Based
OPTION1 Proposed Type I OPTION3 VE Based OPTION2 Proposed Type II

1
Structural Capacity Depreciation Factor, f sc
0.9

Depreciated Structural Capacity Factor

0.9
0.8 0.7

OPTION3: VE Based

0.8
0.7 Critical Zone 0.6

Critical Zone 0.6
0.5

© 2009 Kensetsu Kaihatsu Limited

0.5
0.4

Terminal Line 0.4 0.3
0.2

Terminal Line

0.3
0.2 0.1

0.1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
Time Progression, Nt (years)

0

2

4

6

8

10

12

14

16

18

20

22

Time Progression, Nt (Years)

Figure 8.2.7 Graphical Depiction of Depreciated Structural Capacity Factor and Resulting �������� “WITH Maintenance” Scenario as well as “WithOUT Maintenance” effect for Varying Designs

Page 127

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

The following derivations can be made from Tables 8.2.2 ~ 8.2.8 and Figs. 8.2.1 ~ 8.2.7. 1. All Designs are adequate enough to serve the 20-years design life provided that periodic and routine maintenance is consistently undertaken accordingly. 2. OPTION1 (Proposed Type I Design) and OPTION2 (Proposed Type II Design) Exhibit the highest resistance to structural capacity deterioration. 3. Without maintenance, the characteristic curves of all Designs will exceed the Critical Zone between approximately 8 and 10 years, and tend to approach the Terminal Line between 11 and 14 years. 4. The most resilient designs are the Proposed Type I and Type II Designs, which indicate that even under extreme conditions (excluding natural disasters such as El Nino, Earthquakes, Tsunamis, recurrent seimic action etc), their Design Life may extend to as long as 12 ~ 14 years. 5. Consequently It can be derived that Without Maintenance there will prevail a need for intervention to undertake recarpeting (resurfacing). This would be approximately 11 and 13 years for the ORIGINAL and US FAA/ICAO Designs and 13 to 14 years for the Proposed Designs.

© 2009 Kensetsu Kaihatsu Limited

Page 128

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

CHAPTER 9

9. CONCLUSIONS AND RECOMMENDATIONS

9.1 Main Conclusions In this Study, comprehensive testing and analysis have been undertaken for purposes of realizing the most Value Engineering based design for the Songwe Airport Pavement Structure in Mbeya District.

Based on the derivations noted in this Report, the following main conclusions can be made.

1. The in-situ Pozzolanic materials existing within the vicinity of the Project Area are certainly suitable for the construction of the Base Course pavement layer. 2. The detailed laboratory and in-situ experimental testing, technical evaluation, geotechnical engineering investigations and analyses indicate that the existing ground and pavement structure exhibit much higher bearing capacity and strength responses in comparison to the values that may have been considered in the Original Design. 3. Based on the conclusion in 2. above, It is most likely that the Original Design did not take into account the pozzolanic cementetious nature of the existing geomaterial as well as its immediate and positive response to compaction and the effects of time related consolidation, thixotropy and creep (secondary consolidation) that are known to immensely enhance the engineering properties of ground foundations and geomaterials . 4. This anomaly and/or misconception seems to have influenced the Original Design Concept, selection of materials and design of the pavement layer configuration. 5. Due mainly to the nature of the material and the existing natural ground, the magnitude of the bearing capacity, strength and deformation resistance of the existing subbase and subgrade supersedes to a large extent, values specified as material requirements for base course layers by International Agencies and Researchers. Conaequently, the 3% cement treated (stabilized) Pozzolanic materials are suitable for use for the construction of the Base Course layer.

© 2009 Kensetsu Kaihatsu Limited

6. The Reviewed (Proposed Type I and Type II) Designs satisfy all the engineering properties and VE aspects. 7. The Reviewed Designs (Proposed Type I and Type II) are not only cost-effective but also significantly enhance the engineering properties of the composite pavement structure.

Page 129

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

9.2 Basic Recommendations

From the foregoing analysis, discussions and conclusions, the following recommendations can be made accordingly.

1. The Original (Existing) Design be reviewed accordingly. 2. Cost-benefit analyses be undertaken for the Proposed Type I and Type II Designs to determine which, amongst the two, would be most optimum. 3. The Reviewed most optimum Design be adopted accordingly.

© 2009 Kensetsu Kaihatsu Limited

Page 130

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

MAIN REFERENCES Ampadu, S.K (1988): The influence of initial shear on undrained Behavior of normally consolidated Kaolin, Master Thesis, University of Tokyo. Bejerrum, L., 1993. Problems of soil mechanics and construction on soft clay and structurally unstable soils (collapsible, expansive and other). In Proc. 8th Int. Conference on SMFE, Moscow. P111~159. Blyth, F.G.H., & de Freitas M.H>(1998) A Geology for Engineers 7th Edition. Arnold, A member of Hodder Headline Group LONDON. SYDNEY. AUCKLAND.Bulletin of Earthquake Resistant Structure Research Center No. 27 1994. dependence on Frequency of the Failure process of a slope Made up of Coarse Particles. K. Konagai and T. Sato. Institute of Industrial Science University of Tokyo. Burland, J.B. and Wroth, C.P., (1974) Review Paper : Settlement of buildings and associated damage, in Proceeding of the Conference on Settlement of Structures, Pentech Press, Cambridge, 1974. pp. 611~654 Burland, J.B., Borroms, B.B., and De Mello, V., (1977) Behaviour of foundations and structures Proceedings of the 9th International Conference on Soil Mechanics, Tokyo, 1977, Session 2 Burland, J.B (1990); On the compressibility and shear strength on clays and shades at constant water content, Geotechnique, Vol. 2, PP,251. Construction Project Consultant (1995). Tana Basin Road Development Project, Phase II Materials Report Vo. 3 Construction Project Consultant Inc., May, 2000, Hydrological Review and Annalyses for Hydraulic Design of Bridge and Major Culvert Structures and Determination of Areas of Protection, Volume I & II, Tana Basin Road Project Phase II Construction Project Consultant Inc., July, 2000 Engineering Report on the Design and Construction of Reinforced Earth Embankments (The Terre Armee Method), Tana Basin Road Project Phase II. Construction Project Consultant, 2001a. A Brief Report on the Computation of Capping Layer Thickness with Reference to Native Subgrade Bearing Capacity, CPC Internal Report Construction Project Consultants, 2001b. Analysis And Evaluation of the Structural Capacity and Serviceability Level of the Existing Road Pavement (Phase III), CPC Internal Report Construction Project Consultants, 2001c. Characterization of Black Cotton Soil as a Pavement Foundation Material Based On Comprehensive Analysis (Stage 1), CPC Internal Report CPC Consultants. Tana Basin Road Development Project, Phase II. Materials Report Vol. 3 Tatsuoka, F. & Shibuya, S. Report of the institute of industrial science the University of Tokyo Vol. 37 No. (serial No. 235) (1992) Deformation Characteristics of soils and Rocks from Field and Labortory Tests Gidigasu. M.D. 1974a. Review of Identification of Problem Laterite Soils in Highway engineering, Transport Research Board, Washington Recording, I, 497:96~111 Gidigasu. M.D. 1988. Potential application of engineering pedology in shallow foundation engineering on tropical residual soils. In Geomechanics in Tropical Coils. Proc. of the II Int’l Conference on Geomechanics in Tropical Soils, Singapore, 1,17~24. Gono, k., Mukabi, J.N., Koishikawa, K., Hatekayama, R., Feleke G., Demoze W., Zelalem A., (2003a). Characterization of Some Engineering Aspects of Black Cotton Soils as Pavement Foundation Materials, to be published in the proceedings of the International Civil Engineering Conference on Sustainable development in the 21st Century. Hansen, J. Brinch, (1968) A revised extended formula for bearing capacity, Danish Geotechnical Institute Bulleti No. 28 and code of Practice for Foundation Engineering Denish Geotechnical Institute Bulletin No. 32 (1978) Hardin, B.O and Drnevich, V.P. (1972), Shear-modulus and damping in soils : measurement and parameter effects, Jouranl of the Soil Mechanics and Foundations Division, ASCE, Vol. 98, No. SM6:603-624

© 2009 Kensetsu Kaihatsu Limited

Page 131

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Horii, N., Toyosawa, Y.& Ampadu, S.K Undrained shear characteristics of soft clay after cyclic loading .pp. 113~118.Housner, G. W.: The Behavior of Inverted Pendulum Structures During Earthquakes, Bull. of the Seismological Society of America, Vol. 53, No. 2, pp. 403-417, 1963. Honsen, J. Brinch, (1961) A general formula for bearing capacity, Danish Geotechnical Institute Bulletin No. 11 Imad L.Al-Qadi, Gerardo W. Flintsch, Amara Loulizi, Samer Lahouar & Walid M. Nassar Pavement Instrumentation Responses at the Virginia Smart Road. IRF Road World Congress, Paris, June 2001. Japan Road Bureau, Japan. 1993. In Road Design Manual, Vol. I (in Japanese). Jardine, R.J. 1985. Investigations of pile-soil behavior, with special reference to the foundation of offshore structures. PhD Thesis, University of London. JICA Study Team, 1999. The Study on Rural Roads Improvement In Western Kenya-Materials Testing Analyses and Countermeasures for Design Purposes, Feasilibility Study by The Government of Japan And The Government of Kenya.Jardine, R.J. (1995): One perspective of the pre-failure deformation characteristics of some geomaterials, IS Hokkaido’ 94,2,pp.855-885. Konagai1 Kazuo and Sato2 Takeshi. Dependence on Frequency of the Failure Process of Slope Made up of coarse Particles. pp. 33~39 K.J. McManus, G. Lu and D. Ruan, The Effects on a Bridge Superstructure of Dynamic Loads Generated by Long Wavelength Roughness in Road Surfaces. IRF Road World Congress, Paris, June 2001. Meyerh of, G.G., (1963) some recent research on bearing capacity of foundations, Canadian Geotechnical Journal, 1, 16-26. Ministry of Transport & Public Works, Kenya, 1981. Materials and Pavement Design for New Roads. In Road Design Manual Part III. Ministry of Public Works & Housing Republic of Kenya, March 1999. Report to OECF Appraisal Mission for the Additional Loan to “Tana Basin Road Project” in the Republic of Kenya, Volume I & II. Mukabi, J.N.(1991): Behavior of clays for a wide range of strain in Triaxial compression, Msc. Thesis, University of Tokyo. Mukabi, J. N. (1995): Deformation Characteristics of small strains of clays in triaxial tests PhD Thesis, Univ. of Tokyo. Mukabi, J.N. (1998):Con-Aid Research and Development Proposal. Mukabi.,J.N., Murunga P.A, Wambura.J.H. & Maina J.N., Behavior of con-Aid treated fine grained Kenyan soils. Geotechnics for Developing Africa, Wardle, Blight & Fourie (eds) 1999 Balkema, Rotterdam, ISBN 90 809 082 5.pp.583~519. Mukabi J.N & Tatsuoka, F. 1995. Effects of swelling and saturation of Unsaturated Soil Behaviour and Applications, Int. Symposium on the Behaviour of Unsaturated Soils, University of Nairobi, Nairobi, Kenya. Mukabi J.N & Tatsuoka, F., Kohata, Y. & Akino, N. 1994b. Small strain stiffness of Pleistocene clays. Proc. Int.Symp. on pre-failure Deformation Characteristics of Geomaterials, IS-Hokkaid. ‘94’ Balkema, Vol. 1, PP. 189-195 Mukabi J.N & Tatsuoka, F. (1992); Effects of consolidation stress ratio and strain rate on the peak stress ratio of Kaolin, the 27th Annual meeting of the JSSMFE, Kochi, PP.655~6 Mukabi J.N. & Tatsuoka, F. (1994); Small strain behavior in triaxial compression of lightly over consolidated Kaolin, proc. 49th Annual Conf. Of JSCE, III, pp.296~297Mukabi J.N & Tatsuoka, F. 1999. Effects of stress path and ageing in reconsolidation on deformation characteristics of stiff natural clays. Proc. 2nd I.S on prefailure characteristic of geomaterials, Torino. Mukabi, J.N 1999. The Study on Rural Roads Improvement in Western Kenya – Materials Testing Analyses and Countermeasures for Design Purposes. In Internal Reports and Correspondence, Japan International Cooperation Agency (JICA) & Ministry of Roads & Public Works, Kenya. Mukabi, J.N. 2000. The design and construction of Reinforced Earth Embankments. In Internal Reports and Correspondence, The Terre Armee Method, 2000. CPC, Nairobi.

© 2009 Kensetsu Kaihatsu Limited

Page 132

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

© 2009 Kensetsu Kaihatsu Limited

Mukabi, J.N & Tatsuoka, F. 1994, 1999. Small strain behaviour intriaxial compression of lightly over-consolidated Kaolin. In Proc. 49th Annual Conf. of JSCE, III: 286-297. Influence of reconsolidation stress history and strain rate on the behaviour of kaolin over a wide range of strain. In Wardle, Blight & fourie (eds), Geotechniques for Developing Africa: Proc. 12th African Regional Conf. ISSMGE Durban, 1999. Balkema, Rotterdam. Mukabi, J.N. 2001a. Theoretical and empirical basis for a method of determining the optimum batching ratio for mechanical stabilization of geomaterials. In Proc. 14th IRF road World Congress, Paris, June 2001. Mukabi, J.N & Shimizu, N. 2001b. Strength and deformation characteristics of mechanically stabilized road construction materials based on a new batching ratio method. In Proc. 14th IRF Road World Congress, paris, June 2001. Mukabi, J.N. Njoroge, B.N. & Toda, T. 2001c. pragmatic method of evaluating design parameters adopting Kenyan tropical soils for pavement structure, In Procl 4th IRF Road World Congress, Paris, June 2000. Mukabi, J.N, 2001d. Derivation and application of consolidation and shear stress ratio functions with reference to Critical State analysis of N.C clays. In Proc. ISSMGE Istabul International Conference. August 2001. Mukabi, J.N., 2002c. Some Recent Advances in highway and bridge foundation engineering, Seminar for Ethiopian Roads Authority and Japan Overseas Development Assistance Ethiopia. Mukabi, J.N., Gono K., Koishikawa K., Feleke G., Hatekayam H., Demoze W., R., Kunioka H., Zelalem A., (2003a). Innovating Modified NDT/DT Techniques for the Evaluation of An Existing Pavement StructureMethod of Testing, to be published in the proceedings of the International Civil Engineering Conference on Sustainable development in the 21st Century. Mukabi, J.N., Gono K., Koishikawa K., Feleke G., Hatekayam R., Demoze W., Kunioka H., Zelalem A., (2003b). Innovating Modified NDT/DT Techniques for the Evaluation of An Existing Pavement StructureTheoretical Considerations and Experimental Results, to be published in the proceedings of the International Civil Engineering Conference on Sustainable development in the 21st Century. Mukabi, J.N., Feleke G., Demoze W., Zelalem A., (2003c). Impact of Environmental Factors on the Performance of Highway Pavement Structures, to be published in the proceedings of the International Civil Engineering Conference on Sustainable development in the 21st Century. Newill, R.J. (1961). A Laboratory Investigation of Two Red Clays from Kenya, Geotechnique, 11(4) 302~318.Pandian, N.S., Nagaraj, T.S. & Sivakumar Banu, G.L (1993). Tropical Clays, Part II. Engineering behaviour. J. Geotech. Engrag., ASCE. Peck, R.B., Hanson, W.E. & Thornburn, T.H 1967. (2nd ed) Foundation Engineering, 271-276. New York, John Wiley. Richart, Jr., F.E. (1977); Dynamic stress-strain relationships for soils, S-SO-A ,Proc. Of 9th ICSMFE, Tokyo, 3, pp.189-195. Road Research. Catalogue of road surface deficiencies. 1978 Organization for economic cooperation and development. Road Research Institute. MOC, Japan. 1990 Specifications for road and bridge design, Vol. I & IV. (in Japanese) Road Research Laboratory, 1970. A guide to the structural design of pavements for new road. Road Note No. 29. Road Transport Research. Pavement Management Systems. Paris, 1987 Organization for economic cooperation and development. Skempton, A.W and MacDonald, D.H. (1956), The allowable Settlement of buildings, Proceedings, of the Institution of Civil Engineers, part 3, 5, 727-784 Savage, P.F. & Leou, J. (1998). Guidelines on Use of CON-AID Liquid Chemical Stabilizer. Savage, P.F. (1998). Some Experiences on the Use of Con-Aid: A Water-Soluble Ionic Additive, University of Pretoria.Tatsuoka Fumio, Lo Presti Diego and Kohata Yukihiro, April 2-7, 1995, Third International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics.

Page 133

Construction of Pavements and Buildings for Songwe Airport in Songwe, Mbeya - Tanzania |2009

Shultze, E. and sheriff, G., Prediction of Settlement from evaluated settlement observations for sand, Proceedings of the 8th International Conference on Soil Mechanics, Moscow, 1973, Vol. 1, pp. 225. Tatsuoka, F, Jardine, R. J., Lopresti, D., Benedetto, D. H. and Kodaka, T. (1997). Characterizing the pre-failure Deformation Properties of Geomaterials, Theme lecture ICSMFE, Hamburg, vol. 4. pp.2129-2164. Tatsuoka, F. 1992 Roles of facing rigidity in soil Reinforcing, Theme Lecture for International Symposium, Kyushu,Japan. Tatsuoka, F, Jardine, R. J., Lopresti, D., Benedetto, D. H. and Kodaka, T. (1999). Characterizing the pre-failure Deformation Properties of Geomaterials, Theme lecture ICSMFE, Hamburg, 1997, vol. 4. pp.21292164.2,pp.947-1063. Tatsuoka, F. and Kohata, Y. (1995): Stiffness of hard soils and soft rocks in engineering applications, Keynote Lecture, IS-Hokkaido ’94,Vol. Terzaghi, K. & Peck, R.b 1967. (2nd ed) Soil Mechanics in engineering practice, 310. New York, John Wiley. Towhata, I., Kawasaki, Y., Harada, N. & Sunaga, M. Contraction of soil subjected to traffic-type stress application. Proc. Int. Symp. On Pre-failure Deforemation Characteristics of Geomaterials, IS-Hokkado 94, Balkema Vol. 1, pp. 305~310. Transport and Road Research Laboratory. 1977. A guide to the structural design of bitument surfaced roads in tropical and sub-topical countries. Road Note No. 31Vanghn, P.R. 1985. Geotechnical Characteristics of residual soils. In J. Geotech. Engrg. ASCE, III(1) 77~94. Yoder, E.J & Witczak, M.W; (1975). Principles of Pavement Design Second Edition, A Wile-Interscience Publicaton-John Wiley-Sons, Inc.

© 2009 Kensetsu Kaihatsu Limited

Page 134


				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:917
posted:1/14/2010
language:English
pages:155